diff --git a/backend/app/services/board_lifecycle.py b/backend/app/services/board_lifecycle.py
index f70a4840..a7ec2d74 100644
--- a/backend/app/services/board_lifecycle.py
+++ b/backend/app/services/board_lifecycle.py
@@ -23,6 +23,7 @@ from app.models.board_webhooks import BoardWebhook
 from app.models.organization_board_access import OrganizationBoardAccess
 from app.models.organization_invite_board_access import OrganizationInviteBoardAccess
 from app.models.tag_assignments import TagAssignment
+from app.models.task_custom_fields import BoardTaskCustomField, TaskCustomFieldValue
 from app.models.task_dependencies import TaskDependency
 from app.models.task_fingerprints import TaskFingerprint
 from app.models.tasks import Task
@@ -84,6 +85,12 @@ async def delete_board(session: AsyncSession, *, board: Board) -> OkResponse:
             col(TagAssignment.task_id).in_(task_ids),
             commit=False,
         )
+        await crud.delete_where(
+            session,
+            TaskCustomFieldValue,
+            col(TaskCustomFieldValue.task_id).in_(task_ids),
+            commit=False,
+        )
     # Keep teardown ordered around FK/reference chains so dependent rows are gone
     # before deleting their parent task/agent/board records.
     await crud.delete_where(
@@ -129,6 +136,11 @@ async def delete_board(session: AsyncSession, *, board: Board) -> OkResponse:
         OrganizationInviteBoardAccess,
         col(OrganizationInviteBoardAccess.board_id) == board.id,
     )
+    await crud.delete_where(
+        session,
+        BoardTaskCustomField,
+        col(BoardTaskCustomField.board_id) == board.id,
+    )
 
     # Tasks reference agents and have dependent records.
     # Delete tasks before agents.
diff --git a/backend/tests/test_boards_delete.py b/backend/tests/test_boards_delete.py
index bd5809fd..228cdb69 100644
--- a/backend/tests/test_boards_delete.py
+++ b/backend/tests/test_boards_delete.py
@@ -64,13 +64,14 @@ async def test_delete_board_cleans_org_board_access_rows() -> None:
     deleted_table_names = [statement.table.name for statement in session.executed]
     assert "organization_board_access" in deleted_table_names
     assert "organization_invite_board_access" in deleted_table_names
+    assert "board_task_custom_fields" in deleted_table_names
     assert board in session.deleted
     assert session.committed == 1
 
 
 @pytest.mark.asyncio
 async def test_delete_board_cleans_tag_assignments_before_tasks() -> None:
-    """Deleting a board should remove task-tag links before deleting tasks."""
+    """Deleting a board should remove task-linked rows before deleting tasks."""
     session: Any = _FakeSession(exec_results=[[], [uuid4()]])
     board = Board(
         id=uuid4(),
@@ -87,7 +88,11 @@ async def test_delete_board_cleans_tag_assignments_before_tasks() -> None:
 
     deleted_table_names = [statement.table.name for statement in session.executed]
     assert "tag_assignments" in deleted_table_names
+    assert "task_custom_field_values" in deleted_table_names
     assert deleted_table_names.index("tag_assignments") < deleted_table_names.index("tasks")
+    assert deleted_table_names.index("task_custom_field_values") < deleted_table_names.index(
+        "tasks"
+    )
 
 
 @pytest.mark.asyncio