diff --git a/pkg/knative/deployer.go b/pkg/knative/deployer.go
index 1bd011d142..4cb2f931d5 100644
--- a/pkg/knative/deployer.go
+++ b/pkg/knative/deployer.go
@@ -9,6 +9,7 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
 	"time"
 
@@ -410,6 +411,46 @@ func createTriggers(ctx context.Context, f fn.Function, client clientservingv1.K
 			return err
 		}
 	}
+
+	// Clean up stale triggers that are no longer in the desired subscription set.
+	triggerPrefix := fmt.Sprintf("%s-function-trigger-", ksvc.GetName())
+	existingTriggers, err := eventingClient.ListTriggers(ctx)
+	if err != nil {
+		if errors.IsNotFound(err) || strings.HasPrefix(err.Error(), "no or newer Knative Eventing API found on the backend") {
+			return nil
+		}
+		return fmt.Errorf("knative deployer failed to list triggers for cleanup: %v", err)
+	}
+	triggerNames := make([]string, len(existingTriggers.Items))
+	for i, t := range existingTriggers.Items {
+		triggerNames[i] = t.Name
+	}
+	return deleteStaleTriggers(triggerNames, triggerPrefix, len(f.Deploy.Subscriptions), func(name string) error {
+		return eventingClient.DeleteTrigger(ctx, name)
+	})
+}
+
+// deleteStaleTriggers removes triggers whose numeric index suffix is >= desiredCount.
+// The knative deployer names triggers as <prefix><index>. If the subscription count
+// decreases, triggers with higher indices become orphaned and must be cleaned up.
+func deleteStaleTriggers(triggerNames []string, triggerPrefix string, desiredCount int, deleteFn func(name string) error) error {
+	for _, name := range triggerNames {
+		if !strings.HasPrefix(name, triggerPrefix) {
+			continue
+		}
+		idxStr := strings.TrimPrefix(name, triggerPrefix)
+		idx, parseErr := strconv.Atoi(idxStr)
+		if parseErr != nil {
+			continue
+		}
+		if idx >= desiredCount {
+			fmt.Fprintf(os.Stderr, "Deleting stale trigger: %s\n", name)
+			delErr := deleteFn(name)
+			if delErr != nil && !errors.IsNotFound(delErr) {
+				return fmt.Errorf("knative deployer failed to delete stale trigger %s: %v", name, delErr)
+			}
+		}
+	}
 	return nil
 }
 
diff --git a/pkg/knative/deployer_test.go b/pkg/knative/deployer_test.go
index e024ffec6e..7966142fdb 100644
--- a/pkg/knative/deployer_test.go
+++ b/pkg/knative/deployer_test.go
@@ -461,3 +461,87 @@ func assertAuth(uname, pwd string, w http.ResponseWriter, r *http.Request) bool
 	_, _ = fmt.Fprintln(w, "Unauthorised.")
 	return false
 }
+
+// TestDeleteStaleTriggers_NoStale ensures no triggers are deleted when all are within range.
+func TestDeleteStaleTriggers_NoStale(t *testing.T) {
+	triggers := []string{"my-func-function-trigger-0", "my-func-function-trigger-1"}
+	prefix := "my-func-function-trigger-"
+	var deleted []string
+	deleteFn := func(name string) error {
+		deleted = append(deleted, name)
+		return nil
+	}
+	err := deleteStaleTriggers(triggers, prefix, 2, deleteFn)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(deleted) != 0 {
+		t.Fatalf("expected no deletions, got %v", deleted)
+	}
+}
+
+// TestDeleteStaleTriggers_DeletesStale ensures triggers beyond desired count are deleted.
+func TestDeleteStaleTriggers_DeletesStale(t *testing.T) {
+	triggers := []string{
+		"my-func-function-trigger-0",
+		"my-func-function-trigger-1",
+		"my-func-function-trigger-2",
+		"my-func-function-trigger-3",
+	}
+	prefix := "my-func-function-trigger-"
+	var deleted []string
+	deleteFn := func(name string) error {
+		deleted = append(deleted, name)
+		return nil
+	}
+	// desiredCount=2 means indices 2 and 3 are stale
+	err := deleteStaleTriggers(triggers, prefix, 2, deleteFn)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(deleted) != 2 {
+		t.Fatalf("expected 2 deletions, got %v", deleted)
+	}
+	if deleted[0] != "my-func-function-trigger-2" || deleted[1] != "my-func-function-trigger-3" {
+		t.Fatalf("unexpected deleted triggers: %v", deleted)
+	}
+}
+
+// TestDeleteStaleTriggers_SkipsNonMatching ensures triggers that don't match the prefix or
+// have unparseable suffixes are skipped.
+func TestDeleteStaleTriggers_SkipsNonMatching(t *testing.T) {
+	triggers := []string{
+		"other-trigger-0",              // wrong prefix
+		"my-func-function-trigger-abc", // unparseable index
+		"my-func-function-trigger-2",   // stale, should be deleted
+	}
+	prefix := "my-func-function-trigger-"
+	var deleted []string
+	deleteFn := func(name string) error {
+		deleted = append(deleted, name)
+		return nil
+	}
+	err := deleteStaleTriggers(triggers, prefix, 1, deleteFn)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(deleted) != 1 || deleted[0] != "my-func-function-trigger-2" {
+		t.Fatalf("expected only trigger-2 deleted, got %v", deleted)
+	}
+}
+
+// TestDeleteStaleTriggers_DeleteError ensures errors from the delete callback are returned.
+func TestDeleteStaleTriggers_DeleteError(t *testing.T) {
+	triggers := []string{"my-func-function-trigger-5"}
+	prefix := "my-func-function-trigger-"
+	deleteFn := func(name string) error {
+		return fmt.Errorf("connection refused")
+	}
+	err := deleteStaleTriggers(triggers, prefix, 1, deleteFn)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), "connection refused") {
+		t.Fatalf("expected 'connection refused' in error, got: %v", err)
+	}
+}