diff --git a/src/sentry/taskworker/workerchild.py b/src/sentry/taskworker/workerchild.py
index f5e66a0ac24099..ccf5391a610bf8 100644
--- a/src/sentry/taskworker/workerchild.py
+++ b/src/sentry/taskworker/workerchild.py
@@ -310,6 +310,13 @@ def _execute_activation(task_func: Task[Any, Any], activation: TaskActivation) -
                 )
                 span.set_data(SPANDATA.MESSAGING_SYSTEM, "taskworker")
 
+            # TODO(taskworker) remove this when doing cleanup
+            # The `__start_time` parameter is spliced into task parameters by
+            # sentry.celery.SentryTask._add_metadata and needs to be removed
+            # from kwargs like sentry.tasks.base.instrumented_task does.
+            if "__start_time" in kwargs:
+                kwargs.pop("__start_time")
+
             try:
                 task_func(*args, **kwargs)
                 transaction.set_status(SPANSTATUS.OK)
diff --git a/tests/sentry/taskworker/test_worker.py b/tests/sentry/taskworker/test_worker.py
index bc8bb93a19cc8e..eff5b7c833b1f0 100644
--- a/tests/sentry/taskworker/test_worker.py
+++ b/tests/sentry/taskworker/test_worker.py
@@ -299,6 +299,35 @@ def test_child_process_complete(mock_capture_checkin) -> None:
     assert mock_capture_checkin.call_count == 0
 
 
+@pytest.mark.django_db
+def test_child_process_remove_start_time_kwargs() -> None:
+    activation = TaskActivation(
+        id="6789",
+        taskname="examples.will_retry",
+        namespace="examples",
+        parameters='{"args": ["stuff"], "kwargs": {"__start_time": 123}}',
+        processing_deadline_duration=100000,
+    )
+    todo: queue.Queue[TaskActivation] = queue.Queue()
+    processed: queue.Queue[ProcessingResult] = queue.Queue()
+    shutdown = Event()
+
+    todo.put(activation)
+    child_process(
+        todo,
+        processed,
+        shutdown,
+        max_task_count=1,
+        processing_pool_name="test",
+        process_type="fork",
+    )
+
+    assert todo.empty()
+    result = processed.get()
+    assert result.task_id == activation.id
+    assert result.status == TASK_ACTIVATION_STATUS_COMPLETE
+
+
 @pytest.mark.django_db
 @mock.patch("sentry.usage_accountant.record")
 def test_child_process_complete_record_usage(mock_record: mock.Mock) -> None: