diff --git a/airflow/utils/json.py b/airflow/utils/json.py
index f59d82009049b..6d1cc5f036d50 100644
--- a/airflow/utils/json.py
+++ b/airflow/utils/json.py
@@ -54,6 +54,6 @@ def _default(obj):
             return float(obj)
         elif k8s is not None and isinstance(obj, k8s.V1Pod):
             from airflow.kubernetes.pod_generator import PodGenerator
-            PodGenerator.serialize_pod(obj)
+            return PodGenerator.serialize_pod(obj)
 
         raise TypeError(f"Object of type '{obj.__class__.__name__}' is not JSON serializable")
diff --git a/airflow/www/views.py b/airflow/www/views.py
index 5bf201be47988..341c759912322 100644
--- a/airflow/www/views.py
+++ b/airflow/www/views.py
@@ -47,6 +47,7 @@
 from sqlalchemy import and_, desc, func, or_, union_all
 from sqlalchemy.orm import joinedload
 from wtforms import SelectField, validators
+from airflow.utils import json as utils_json
 
 import airflow
 from airflow import models, plugins_manager, settings
@@ -2444,7 +2445,7 @@ def task_instances(self):
             ti.task_id: alchemy_to_dict(ti)
             for ti in dag.get_task_instances(dttm, dttm)}
 
-        return json.dumps(task_instances)
+        return json.dumps(task_instances, cls=utils_json.AirflowJsonEncoder)
 
 
 class ConfigurationView(AirflowBaseView):
diff --git a/tests/utils/test_json.py b/tests/utils/test_json.py
index d48f7090413dc..69363b84feb8d 100644
--- a/tests/utils/test_json.py
+++ b/tests/utils/test_json.py
@@ -58,6 +58,29 @@ def test_encode_numpy_float(self):
             '3.76953125'
         )
 
+    def test_encode_k8s_v1pod(self):
+        from kubernetes.client import models as k8s
+
+        pod = k8s.V1Pod(
+            metadata=k8s.V1ObjectMeta(
+                name="foo",
+                namespace="bar",
+            ),
+            spec=k8s.V1PodSpec(
+                containers=[
+                    k8s.V1Container(
+                        name="foo",
+                        image="bar",
+                    )
+                ]
+            )
+        )
+        self.assertEqual(
+            json.loads(json.dumps(pod, cls=utils_json.AirflowJsonEncoder)),
+            {"metadata": {"name": "foo", "namespace": "bar"},
+             "spec": {"containers": [{"image": "bar", "name": "foo"}]}}
+        )
+
     def test_encode_raises(self):
         self.assertRaisesRegex(TypeError,
                                "^.*is not JSON serializable$",