diff --git a/src/blueapi/worker/event.py b/src/blueapi/worker/event.py
index 367464457e..df9b54bb45 100644
--- a/src/blueapi/worker/event.py
+++ b/src/blueapi/worker/event.py
@@ -4,6 +4,7 @@
 
 from bluesky.run_engine import RunEngineStateMachine
 from pydantic import Field, PydanticSchemaGenerationError, TypeAdapter
+from pydantic_core import PydanticSerializationError
 from super_state_machine.extras import PropertyMachine, ProxyString
 
 from blueapi.utils import BlueapiBaseModel
@@ -73,8 +74,8 @@ class TaskResult(BlueapiBaseModel):
     def from_result(cls, result: Any) -> Self:
         type_str = type(result).__name__
         try:
-            value = TypeAdapter(type(result)).dump_python(result)
-        except PydanticSchemaGenerationError:
+            value = TypeAdapter(type(result)).dump_python(result, mode="json")
+        except (PydanticSchemaGenerationError, PydanticSerializationError):
             value = None
         return cls(result=value, type=type_str)
 
diff --git a/tests/unit_tests/worker/test_task_worker.py b/tests/unit_tests/worker/test_task_worker.py
index 4b4d83408c..ee5db34f7f 100644
--- a/tests/unit_tests/worker/test_task_worker.py
+++ b/tests/unit_tests/worker/test_task_worker.py
@@ -893,3 +893,22 @@ def test_plan_module_with_composite_devices_can_be_loaded_before_device_module(
     params = Task(name="injected_device_plan").prepare_params(context_without_devices)
     assert params["composite"].fake_device == fake_device
     assert params["composite"].second_fake_device == second_fake_device
+
+
+@pytest.mark.parametrize(
+    "plan_result,task_result,type_name",
+    (
+        (Unreturnable(foo=1, bar=[]), None, "Unreturnable"),
+        ((Unreturnable(foo=2, bar=[]),), None, "tuple"),
+        (ComplexReturn(foo=3, bar=["a"]), {"foo": 3, "bar": ["a"]}, "ComplexReturn"),
+        ((ComplexReturn(foo=4, bar=["b"]),), [{"foo": 4, "bar": ["b"]}], "tuple"),
+        (ModelReturn(foo=5, bar=["c"]), {"foo": 5, "bar": ["c"]}, "ModelReturn"),
+        ((ModelReturn(foo=6, bar=["d"]),), [{"foo": 6, "bar": ["d"]}], "tuple"),
+        (42, 42, "int"),
+        ((1, 2), [1, 2], "tuple"),
+    ),
+)
+def test_task_result_serialization(plan_result, task_result, type_name):
+    res = TaskResult.from_result(plan_result)
+    assert res.result == task_result
+    assert res.type == type_name