diff --git a/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala b/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala
index 2856a735bf3..33182a7f90a 100644
--- a/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala
+++ b/spark/common/src/main/scala/org/apache/sedona/sql/SedonaSqlExtensions.scala
@@ -22,6 +22,7 @@ import org.apache.sedona.spark.SedonaContext
 import org.apache.spark.SparkContext
 import org.apache.spark.sql.SparkSessionExtensions
 import org.apache.spark.sql.parser.ParserFactory
+import org.apache.spark.sql.sedona_sql.optimization.Box2DCastResolutionRule
 import org.slf4j.{Logger, LoggerFactory}
 
 class SedonaSqlExtensions extends (SparkSessionExtensions => Unit) {
@@ -36,6 +37,11 @@ class SedonaSqlExtensions extends (SparkSessionExtensions => Unit) {
       _ => ()
     })
 
+    // Resolve geometry↔Box2D casts during analysis so the analyzer accepts
+    // `CAST(geom AS box2d)` / `CAST(box AS geometry)` despite Spark's stock cast resolver
+    // refusing arbitrary UDT-to-UDT casts.
+    e.injectResolutionRule(_ => new Box2DCastResolutionRule)
+
     // Inject Sedona SQL parser
     if (enableParser) {
       // Try to inject the Sedona SQL parser but gracefully handle initialization failures.
diff --git a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Constructors.scala b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Constructors.scala
index 57549812512..beac34727dd 100644
--- a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Constructors.scala
+++ b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/Constructors.scala
@@ -554,9 +554,8 @@ private[apache] case class ST_MakeBox2D(inputExpressions: Seq[Expression])
 
 /**
  * Convert a Box2D to a closed rectangular polygon Geometry. Equivalent to PostGIS {@code
- * box2d::geometry}. Exposed as a function rather than a Catalyst implicit cast because UDT-to-UDT
- * implicit casts require Catalyst-level work; ST_GeomFromBox2D lives alongside the other
- * ST_GeomFrom* constructors.
+ * box2d::geometry}. `CAST(box AS geometry)` is also accepted (resolved to this expression by the
+ * Box2D cast resolution rule).
  *
  * @param inputExpressions
  */
diff --git a/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/optimization/Box2DCastResolutionRule.scala b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/optimization/Box2DCastResolutionRule.scala
new file mode 100644
index 00000000000..580fd952752
--- /dev/null
+++ b/spark/common/src/main/scala/org/apache/spark/sql/sedona_sql/optimization/Box2DCastResolutionRule.scala
@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.spark.sql.sedona_sql.optimization
+
+import org.apache.spark.sql.catalyst.expressions.Cast
+import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import org.apache.spark.sql.catalyst.rules.Rule
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.expressions.{ST_Box2D, ST_GeomFromBox2D}
+
+/**
+ * Analyzer rule that resolves Catalyst casts between Sedona UDTs that Spark's stock cast resolver
+ * does not handle. Specifically:
+ *
+ *   - `CAST(geom AS box2d)` → `ST_Box2D(geom)` (planar bounding box of the geometry)
+ *   - `CAST(box AS geometry)` → `ST_GeomFromBox2D(box)` (rectangular polygon from a Box2D)
+ *
+ * Spark's `Cast.canCast` returns `false` for arbitrary UDT-to-UDT casts, so without this rule the
+ * analyzer would reject the cast. We rewrite during analysis (before `CheckAnalysis`) so the
+ * downstream optimizer and codegen path see the expression tree of an ordinary Sedona expression.
+ *
+ * Implicit type coercion (e.g. passing a Geometry into a Box2D-typed function argument without an
+ * explicit cast) is intentionally out of scope here; it requires hooking into Catalyst's type
+ * coercion rules and is tracked separately.
+ */
+class Box2DCastResolutionRule extends Rule[LogicalPlan] {
+
+  override def apply(plan: LogicalPlan): LogicalPlan = plan.transformAllExpressions {
+    case c: Cast
+        if c.child.resolved
+          && c.child.dataType.isInstanceOf[GeometryUDT]
+          && c.dataType.isInstanceOf[Box2DUDT] =>
+      ST_Box2D(Seq(c.child))
+
+    case c: Cast
+        if c.child.resolved
+          && c.child.dataType.isInstanceOf[Box2DUDT]
+          && c.dataType.isInstanceOf[GeometryUDT] =>
+      ST_GeomFromBox2D(Seq(c.child))
+  }
+}
diff --git a/spark/common/src/test/scala/org/apache/sedona/sql/Box2DCastResolutionRuleSuite.scala b/spark/common/src/test/scala/org/apache/sedona/sql/Box2DCastResolutionRuleSuite.scala
new file mode 100644
index 00000000000..322dd370fac
--- /dev/null
+++ b/spark/common/src/test/scala/org/apache/sedona/sql/Box2DCastResolutionRuleSuite.scala
@@ -0,0 +1,70 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.spark.sql.catalyst.expressions.{Alias, AttributeReference, Cast, Expression, Literal}
+import org.apache.spark.sql.catalyst.plans.logical.{LocalRelation, LogicalPlan, Project}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+import org.apache.spark.sql.sedona_sql.expressions.{ST_Box2D, ST_GeomFromBox2D}
+import org.apache.spark.sql.sedona_sql.optimization.Box2DCastResolutionRule
+import org.apache.spark.sql.types.LongType
+import org.scalatest.funspec.AnyFunSpec
+
+class Box2DCastResolutionRuleSuite extends AnyFunSpec {
+
+  private val rule = new Box2DCastResolutionRule
+
+  private def projectExprPlan(input: AttributeReference, expr: Expression): LogicalPlan = {
+    val rel = LocalRelation(input)
+    Project(Seq(Alias(expr, "out")()), rel)
+  }
+
+  describe("Box2DCastResolutionRule") {
+    it("rewrites Cast(geometry-typed expression, Box2DUDT) into ST_Box2D") {
+      val geomAttr = AttributeReference("g", GeometryUDT(), nullable = true)()
+      val cast = Cast(geomAttr, Box2DUDT)
+      val rewritten = rule(projectExprPlan(geomAttr, cast))
+      val outExpr =
+        rewritten.asInstanceOf[Project].projectList.head.asInstanceOf[Alias].child
+      assert(outExpr.isInstanceOf[ST_Box2D])
+      assert(outExpr.asInstanceOf[ST_Box2D].inputExpressions == Seq(geomAttr))
+      assert(outExpr.dataType.isInstanceOf[Box2DUDT])
+    }
+
+    it("rewrites Cast(Box2D-typed expression, GeometryUDT) into ST_GeomFromBox2D") {
+      val boxAttr = AttributeReference("b", Box2DUDT, nullable = true)()
+      val cast = Cast(boxAttr, GeometryUDT())
+      val rewritten = rule(projectExprPlan(boxAttr, cast))
+      val outExpr =
+        rewritten.asInstanceOf[Project].projectList.head.asInstanceOf[Alias].child
+      assert(outExpr.isInstanceOf[ST_GeomFromBox2D])
+      assert(outExpr.asInstanceOf[ST_GeomFromBox2D].inputExpressions == Seq(boxAttr))
+      assert(outExpr.dataType.isInstanceOf[GeometryUDT])
+    }
+
+    it("leaves unrelated casts untouched") {
+      val geomAttr = AttributeReference("g", GeometryUDT(), nullable = true)()
+      val cast = Cast(Literal(1), LongType)
+      val rewritten = rule(projectExprPlan(geomAttr, cast))
+      val outExpr =
+        rewritten.asInstanceOf[Project].projectList.head.asInstanceOf[Alias].child
+      assert(outExpr.isInstanceOf[Cast])
+    }
+  }
+}
diff --git a/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index b56ed11c875..eaabd227713 100644
--- a/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-3.4/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,19 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.GeometryUDT
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Override the method to handle the geometry data type
-   * @param ctx
-   * @return
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
+      case "BOX2D" => Box2DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-3.4/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala b/spark/spark-3.4/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
new file mode 100644
index 00000000000..d9a62dabbe5
--- /dev/null
+++ b/spark/spark-3.4/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box2D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+
+class Box2DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box2d)` / `CAST(... AS geometry)` parsing requires Sedona's
+   * `SedonaSqlAstBuilder` to be active. The test base randomizes
+   * `spark.sedona.enableParserExtension` across CI runs, and `SparkContext` is JVM-singleton so
+   * the active value can differ from this suite's session-level config. Probe directly by parsing
+   * a tiny CAST: this matches the behavior the SQL tests actually depend on, and caches the
+   * answer for the rest of the suite. DataFrame `.cast(...)` tests run unconditionally because
+   * the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box2d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry ↔ Box2D Catalyst cast") {
+
+    it("DataFrame .cast(Box2DUDT) rewrites to ST_Box2D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 10 20)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("DataFrame .cast(GeometryUDT) rewrites to ST_GeomFromBox2D") {
+      val df =
+        sparkSession.sql("SELECT ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS b")
+      val wkt = df
+        .select(col("b").cast(GeometryUDT()).alias("g"))
+        .selectExpr("ST_AsText(g) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("DataFrame round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val wkt = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).cast(GeometryUDT()).alias("env"))
+        .selectExpr("ST_AsText(env) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("DataFrame .cast(Box2DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box2d) returns the planar bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 10 20)') AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("SQL CAST(box AS geometry) returns the rectangular polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS geometry)` syntax")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("SQL round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS ...)` between UDTs")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box2d) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("SQL CAST(NULL geometry AS box2d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+  }
+}
diff --git a/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index b56ed11c875..eaabd227713 100644
--- a/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-3.5/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,19 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.GeometryUDT
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Override the method to handle the geometry data type
-   * @param ctx
-   * @return
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
+      case "BOX2D" => Box2DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-3.5/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala b/spark/spark-3.5/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
new file mode 100644
index 00000000000..d9a62dabbe5
--- /dev/null
+++ b/spark/spark-3.5/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box2D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+
+class Box2DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box2d)` / `CAST(... AS geometry)` parsing requires Sedona's
+   * `SedonaSqlAstBuilder` to be active. The test base randomizes
+   * `spark.sedona.enableParserExtension` across CI runs, and `SparkContext` is JVM-singleton so
+   * the active value can differ from this suite's session-level config. Probe directly by parsing
+   * a tiny CAST: this matches the behavior the SQL tests actually depend on, and caches the
+   * answer for the rest of the suite. DataFrame `.cast(...)` tests run unconditionally because
+   * the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box2d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry ↔ Box2D Catalyst cast") {
+
+    it("DataFrame .cast(Box2DUDT) rewrites to ST_Box2D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 10 20)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("DataFrame .cast(GeometryUDT) rewrites to ST_GeomFromBox2D") {
+      val df =
+        sparkSession.sql("SELECT ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS b")
+      val wkt = df
+        .select(col("b").cast(GeometryUDT()).alias("g"))
+        .selectExpr("ST_AsText(g) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("DataFrame round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val wkt = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).cast(GeometryUDT()).alias("env"))
+        .selectExpr("ST_AsText(env) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("DataFrame .cast(Box2DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box2d) returns the planar bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 10 20)') AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("SQL CAST(box AS geometry) returns the rectangular polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS geometry)` syntax")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("SQL round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS ...)` between UDTs")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box2d) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("SQL CAST(NULL geometry AS box2d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+  }
+}
diff --git a/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index b56ed11c875..eaabd227713 100644
--- a/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-4.0/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,19 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.GeometryUDT
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Override the method to handle the geometry data type
-   * @param ctx
-   * @return
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
+      case "BOX2D" => Box2DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-4.0/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala b/spark/spark-4.0/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
new file mode 100644
index 00000000000..d9a62dabbe5
--- /dev/null
+++ b/spark/spark-4.0/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box2D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+
+class Box2DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box2d)` / `CAST(... AS geometry)` parsing requires Sedona's
+   * `SedonaSqlAstBuilder` to be active. The test base randomizes
+   * `spark.sedona.enableParserExtension` across CI runs, and `SparkContext` is JVM-singleton so
+   * the active value can differ from this suite's session-level config. Probe directly by parsing
+   * a tiny CAST: this matches the behavior the SQL tests actually depend on, and caches the
+   * answer for the rest of the suite. DataFrame `.cast(...)` tests run unconditionally because
+   * the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box2d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry ↔ Box2D Catalyst cast") {
+
+    it("DataFrame .cast(Box2DUDT) rewrites to ST_Box2D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 10 20)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("DataFrame .cast(GeometryUDT) rewrites to ST_GeomFromBox2D") {
+      val df =
+        sparkSession.sql("SELECT ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS b")
+      val wkt = df
+        .select(col("b").cast(GeometryUDT()).alias("g"))
+        .selectExpr("ST_AsText(g) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("DataFrame round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val wkt = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).cast(GeometryUDT()).alias("env"))
+        .selectExpr("ST_AsText(env) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("DataFrame .cast(Box2DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box2d) returns the planar bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 10 20)') AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("SQL CAST(box AS geometry) returns the rectangular polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS geometry)` syntax")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("SQL round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS ...)` between UDTs")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box2d) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("SQL CAST(NULL geometry AS box2d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+  }
+}
diff --git a/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala b/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
index b56ed11c875..eaabd227713 100644
--- a/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
+++ b/spark/spark-4.1/src/main/scala/org/apache/sedona/sql/parser/SedonaSqlAstBuilder.scala
@@ -20,19 +20,19 @@ package org.apache.sedona.sql.parser
 
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
 import org.apache.spark.sql.execution.SparkSqlAstBuilder
-import org.apache.spark.sql.sedona_sql.UDT.GeometryUDT
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
 import org.apache.spark.sql.types.DataType
 
 class SedonaSqlAstBuilder extends SparkSqlAstBuilder {
 
   /**
-   * Override the method to handle the geometry data type
-   * @param ctx
-   * @return
+   * Recognize Sedona UDT names (GEOMETRY, BOX2D) as primitive data types so SQL `CAST(... AS
+   * geometry)` / `CAST(... AS box2d)` parse to the matching UDT.
    */
   override def visitPrimitiveDataType(ctx: PrimitiveDataTypeContext): DataType = {
     ctx.getText.toUpperCase() match {
       case "GEOMETRY" => GeometryUDT()
+      case "BOX2D" => Box2DUDT
       case _ => super.visitPrimitiveDataType(ctx)
     }
   }
diff --git a/spark/spark-4.1/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala b/spark/spark-4.1/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
new file mode 100644
index 00000000000..d9a62dabbe5
--- /dev/null
+++ b/spark/spark-4.1/src/test/scala/org/apache/sedona/sql/Box2DCastSuite.scala
@@ -0,0 +1,144 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sedona.sql
+
+import org.apache.sedona.common.geometryObjects.Box2D
+import org.apache.spark.sql.functions.{col, expr}
+import org.apache.spark.sql.sedona_sql.UDT.{Box2DUDT, GeometryUDT}
+
+class Box2DCastSuite extends TestBaseScala {
+
+  /**
+   * SQL `CAST(... AS box2d)` / `CAST(... AS geometry)` parsing requires Sedona's
+   * `SedonaSqlAstBuilder` to be active. The test base randomizes
+   * `spark.sedona.enableParserExtension` across CI runs, and `SparkContext` is JVM-singleton so
+   * the active value can differ from this suite's session-level config. Probe directly by parsing
+   * a tiny CAST: this matches the behavior the SQL tests actually depend on, and caches the
+   * answer for the rest of the suite. DataFrame `.cast(...)` tests run unconditionally because
+   * the resolution rule is always injected.
+   */
+  private lazy val sqlCastSupported: Boolean = {
+    try {
+      sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('POINT (0 0)') AS box2d) AS b")
+        .collect()
+      true
+    } catch {
+      case _: org.apache.spark.sql.catalyst.parser.ParseException => false
+    }
+  }
+
+  describe("Geometry ↔ Box2D Catalyst cast") {
+
+    it("DataFrame .cast(Box2DUDT) rewrites to ST_Box2D") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 10 20)").toDF("wkt")
+      val box = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("DataFrame .cast(GeometryUDT) rewrites to ST_GeomFromBox2D") {
+      val df =
+        sparkSession.sql("SELECT ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS b")
+      val wkt = df
+        .select(col("b").cast(GeometryUDT()).alias("g"))
+        .selectExpr("ST_AsText(g) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("DataFrame round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      import sparkSession.implicits._
+      val df = Seq("LINESTRING (0 0, 5 10)").toDF("wkt")
+      val wkt = df
+        .select(expr("ST_GeomFromText(wkt)").alias("g"))
+        .select(col("g").cast(Box2DUDT).cast(GeometryUDT()).alias("env"))
+        .selectExpr("ST_AsText(env) AS wkt")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("DataFrame .cast(Box2DUDT) on NULL geometry returns null") {
+      val box = sparkSession
+        .sql("SELECT ST_GeomFromText(NULL) AS g")
+        .select(col("g").cast(Box2DUDT).alias("b"))
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+
+    it("SQL CAST(geom AS box2d) returns the planar bbox") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText('LINESTRING (0 0, 10 20)') AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == new Box2D(0.0, 0.0, 10.0, 20.0))
+    }
+
+    it("SQL CAST(box AS geometry) returns the rectangular polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS geometry)` syntax")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(ST_MakeBox2D(ST_Point(0.0, 0.0), ST_Point(2.0, 4.0)) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 4, 2 4, 2 0, 0 0))")
+    }
+
+    it("SQL round-trip Geometry → Box2D → Geometry yields the envelope polygon") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS ...)` between UDTs")
+      val wkt = sparkSession
+        .sql("SELECT ST_AsText(CAST(CAST(ST_GeomFromText('LINESTRING (0 0, 5 10)') AS box2d) AS geometry)) AS w")
+        .collect()
+        .head
+        .getString(0)
+      assert(wkt == "POLYGON ((0 0, 0 10, 5 10, 5 0, 0 0))")
+    }
+
+    it("SQL CAST(NULL geometry AS box2d) returns null") {
+      assume(
+        sqlCastSupported,
+        "Sedona SQL parser extension is required for `CAST(... AS box2d)` syntax")
+      val box = sparkSession
+        .sql("SELECT CAST(ST_GeomFromText(NULL) AS box2d) AS b")
+        .collect()
+        .head
+        .getAs[Box2D]("b")
+      assert(box == null)
+    }
+  }
+}