diff --git a/moto/iot/models.py b/moto/iot/models.py
index b2e6c205e46..a7386c3d1a7 100644
--- a/moto/iot/models.py
+++ b/moto/iot/models.py
@@ -48,6 +48,7 @@ def __init__(
         region_name: str,
     ):
         self.region_name = region_name
+        self.account_id = account_id
         self.thing_id = str(random.uuid4())
         self.thing_name = thing_name
         self.thing_type = thing_type
@@ -80,6 +81,7 @@ def to_dict(
         include_default_client_id: bool = False,
         include_connectivity: bool = False,
         include_thing_id: bool = False,
+        include_thing_group_names: bool = False,
     ) -> Dict[str, Any]:
         obj = {
             "thingName": self.thing_name,
@@ -98,6 +100,14 @@ def to_dict(
             }
         if include_thing_id:
             obj["thingId"] = self.thing_id
+        if include_thing_group_names:
+            iot_backend = iot_backends[self.account_id][self.region_name]
+
+            obj["thingGroupNames"] = []
+            for thing_group in iot_backend.list_thing_groups(None, None, None):
+                if self.arn in thing_group.things:
+                    obj["thingGroupNames"].append(thing_group.thing_group_name)
+
         return obj
 
     @staticmethod
@@ -2298,7 +2308,10 @@ def search_index(self, query_string: str) -> List[Dict[str, Any]]:
         things = [
             thing for thing in self.things.values() if thing.matches(query_string)
         ]
-        return [t.to_dict(include_connectivity=True) for t in things]
+        return [
+            t.to_dict(include_connectivity=True, include_thing_group_names=True)
+            for t in things
+        ]
 
     def create_role_alias(
         self,
diff --git a/tests/test_iot/test_iot_search.py b/tests/test_iot/test_iot_search.py
index 50c8884d201..6da5be2d13f 100644
--- a/tests/test_iot/test_iot_search.py
+++ b/tests/test_iot/test_iot_search.py
@@ -33,6 +33,25 @@ def test_search_things(query_string, results):
         assert thing["connectivity"] == {"connected": True}
 
 
+@mock_aws
+def test_search_things_include_group_names():
+    client = boto3.client("iot", region_name="ap-northeast-1")
+
+    thing_name = "test-thing-name"
+    client.create_thing(thingName=thing_name)
+
+    client.create_thing_group(thingGroupName="TestGroup1")
+    client.create_thing_group(thingGroupName="AnotherGroup")
+    client.create_thing_group(thingGroupName="GroupWithoutMembers")
+
+    client.add_thing_to_thing_group(thingName=thing_name, thingGroupName="TestGroup1")
+    client.add_thing_to_thing_group(thingName=thing_name, thingGroupName="AnotherGroup")
+
+    resp = client.search_index(queryString=f"thingName:{thing_name}")
+    assert len(resp["things"]) == 1
+    assert resp["things"][0]["thingGroupNames"] == ["TestGroup1", "AnotherGroup"]
+
+
 @mock_aws
 @pytest.mark.parametrize(
     "query_string,results",