diff --git a/faststream_outbox/broker.py b/faststream_outbox/broker.py
index f75af73..9bff053 100644
--- a/faststream_outbox/broker.py
+++ b/faststream_outbox/broker.py
@@ -36,6 +36,7 @@
 
 if typing.TYPE_CHECKING:
     from fast_depends.dependencies import Dependant
+    from fast_depends.library.serializer import SerializerProto
     from faststream._internal.context.repository import ContextRepo
     from sqlalchemy import Table
     from sqlalchemy.ext.asyncio import AsyncEngine
@@ -114,6 +115,7 @@ def __init__(  # noqa: PLR0913
         log_level: int = logging.INFO,
         # FastDepends
         apply_types: bool = True,
+        serializer: "SerializerProto | None" = EMPTY,
         # AsyncAPI
         description: str | None = None,
         tags: Iterable[Tag | TagDict] = (),
@@ -121,7 +123,7 @@ def __init__(  # noqa: PLR0913
         self._outbox_table = outbox_table
         engine_state = EngineState(engine)
         client = OutboxClient(engine, outbox_table) if engine is not None else None
-        fd_config = FastDependsConfig(use_fastdepends=apply_types)
+        fd_config = FastDependsConfig(use_fastdepends=apply_types, serializer=serializer)
         broker_config = OutboxBrokerConfig(
             engine_state=engine_state,
             client=client,
@@ -222,7 +224,13 @@ async def publish(  # ty: ignore[invalid-method-override]  # noqa: PLR0913
         if activate_in is not None and activate_at is not None:
             msg = "broker.publish accepts at most one of activate_in / activate_at"
             raise ValueError(msg)
-        payload, hdrs = _encode_payload(body, headers=headers, correlation_id=correlation_id)
+        serializer = self.config.broker_config.fd_config._serializer  # noqa: SLF001
+        payload, hdrs = _encode_payload(
+            body,
+            headers=headers,
+            correlation_id=correlation_id,
+            serializer=serializer,
+        )
         t = self._outbox_table
         values: dict[str, typing.Any] = {"queue": queue, "payload": payload, "headers": hdrs}
         # Server-side compute keeps timing immune to worker/DB clock skew (mirrors
@@ -291,9 +299,10 @@ async def publish_batch(  # ty: ignore[invalid-method-override]
             next_at = _dt.datetime.now(tz=_dt.UTC) + activate_in
         elif activate_at is not None:
             next_at = activate_at
+        serializer = self.config.broker_config.fd_config._serializer  # noqa: SLF001
         rows = []
         for body in bodies:
-            payload, hdrs = _encode_payload(body, headers=headers)
+            payload, hdrs = _encode_payload(body, headers=headers, serializer=serializer)
             row: dict[str, typing.Any] = {"queue": queue, "payload": payload, "headers": hdrs}
             if next_at is not None:
                 row["next_attempt_at"] = next_at
diff --git a/faststream_outbox/envelope.py b/faststream_outbox/envelope.py
index 28a5e30..bc216b5 100644
--- a/faststream_outbox/envelope.py
+++ b/faststream_outbox/envelope.py
@@ -1,25 +1,33 @@
 """Internal payload encoding for ``broker.publish``."""
 
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from faststream.message import gen_cor_id
 from faststream.message.utils import encode_message
 
 
+if TYPE_CHECKING:
+    from fast_depends.library.serializer import SerializerProto
+
+
 def _encode_payload(
     body: Any,
     *,
     headers: dict[str, str] | None = None,
     correlation_id: str | None = None,
+    serializer: "SerializerProto | None" = None,
 ) -> tuple[bytes, dict[str, str]]:
     """
     Serialize *body* into ``(payload_bytes, headers_dict)`` for an outbox row.
 
     *body* may be ``bytes``, a pydantic model, a dataclass, a ``dict``, or any value
     FastStream's ``encode_message`` accepts. *correlation_id* is auto-generated if
-    not supplied so handlers can always rely on it being present.
+    not supplied so handlers can always rely on it being present. *serializer* is
+    forwarded to FastStream's ``encode_message`` — pass the broker's resolved
+    ``FastDependsConfig._serializer`` so pydantic models / dataclasses encode the
+    same way they do for every other FastStream broker.
     """
-    payload, content_type = encode_message(body, serializer=None)
+    payload, content_type = encode_message(body, serializer=serializer)
     out_headers: dict[str, str] = dict(headers or {})
     if content_type and "content-type" not in out_headers:
         out_headers["content-type"] = content_type
diff --git a/tests/test_unit.py b/tests/test_unit.py
index 2f7a1af..414cf1c 100644
--- a/tests/test_unit.py
+++ b/tests/test_unit.py
@@ -1,8 +1,10 @@
 import datetime as _dt
+import json
 import uuid
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
+from pydantic import BaseModel
 from sqlalchemy import MetaData
 from sqlalchemy.dialects import postgresql
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -116,6 +118,21 @@ def test_encode_payload_merges_user_headers() -> None:
     assert headers["content-type"] == "application/json"
 
 
+class _PydanticBody(BaseModel):
+    order_id: int
+    name: str
+
+
+def test_encode_payload_serializes_pydantic_model_with_default_serializer() -> None:
+    """Default broker resolves PydanticSerializer so BaseModel encodes as JSON."""
+    broker = _make_broker()
+    serializer = broker.config.broker_config.fd_config._serializer  # noqa: SLF001
+    body = _PydanticBody(order_id=1, name="x")
+    payload, headers = _encode_payload(body, serializer=serializer)
+    assert json.loads(payload) == body.model_dump()
+    assert headers["content-type"] == "application/json"
+
+
 # --- retry strategies ---
 
 
@@ -312,7 +329,7 @@ async def test_broker_publish_executes_insert_then_pg_notify_on_session() -> Non
     assert "INSERT INTO" in str(insert_stmt)
     params = insert_stmt.compile().params
     assert params["queue"] == "orders"
-    assert params["payload"] == b'{"order_id": 1}'
+    assert json.loads(params["payload"]) == {"order_id": 1}
     assert params["headers"]["content-type"] == "application/json"
     notify_stmt, notify_params = session.execute.await_args_list[1].args
     assert "pg_notify" in str(notify_stmt)
@@ -320,6 +337,30 @@ async def test_broker_publish_executes_insert_then_pg_notify_on_session() -> Non
     assert notify_params["payload"] == "orders"
 
 
+async def test_broker_publish_encodes_pydantic_model() -> None:
+    broker = _make_broker()
+    session = _make_session_mock()
+    body = _PydanticBody(order_id=7, name="alpha")
+    await broker.publish(body, queue="orders", session=session)
+    insert_stmt = session.execute.await_args_list[0].args[0]
+    params = insert_stmt.compile().params
+    assert json.loads(params["payload"]) == body.model_dump()
+    assert params["headers"]["content-type"] == "application/json"
+
+
+async def test_broker_publish_batch_encodes_pydantic_models() -> None:
+    broker = _make_broker()
+    session = _make_session_mock()
+    bodies = [_PydanticBody(order_id=1, name="a"), _PydanticBody(order_id=2, name="b")]
+    await broker.publish_batch(*bodies, queue="orders", session=session)
+    # First execute is the INSERT (executemany), second is pg_notify.
+    insert_call = session.execute.await_args_list[0]
+    rows = insert_call.args[1]
+    assert [json.loads(row["payload"]) for row in rows] == [b.model_dump() for b in bodies]
+    for row in rows:
+        assert row["headers"]["content-type"] == "application/json"
+
+
 async def test_broker_publish_does_not_commit() -> None:
     broker = _make_broker()
     session = _make_session_mock()
@@ -884,6 +925,17 @@ async def handle(body: str) -> None: ...
     assert sub._make_response_publisher(MagicMock()) == ()  # noqa: SLF001
 
 
+async def test_subscriber_client_property_raises_when_broker_has_no_engine() -> None:
+    broker = _make_broker()  # no engine → broker_config.client is None
+
+    @broker.subscriber("orders")
+    async def handle(body: dict) -> None: ...
+
+    sub = next(iter(broker._subscribers))  # noqa: SLF001
+    with pytest.raises(RuntimeError, match="not connected"):
+        _ = sub._client  # noqa: SLF001
+
+
 # --- _open_listen_connection fallback paths ---