diff --git a/py/plugins/google-genai/src/genkit/plugins/google_genai/models/imagen.py b/py/plugins/google-genai/src/genkit/plugins/google_genai/models/imagen.py
index b348891318..8d209be804 100644
--- a/py/plugins/google-genai/src/genkit/plugins/google_genai/models/imagen.py
+++ b/py/plugins/google-genai/src/genkit/plugins/google_genai/models/imagen.py
@@ -206,10 +206,11 @@ def _contents_from_response(self, response: genai_types.GenerateImagesResponse)
         content = []
         if response.generated_images:
             for image in response.generated_images:
+                b64_data = base64.b64encode(image.image.image_bytes).decode('utf-8')
                 content.append(
                     Part(
                         media=Media(
-                            url=base64.b64encode(image.image.image_bytes),
+                            url=f'data:{image.image.mime_type};base64,{b64_data}',
                             contentType=image.image.mime_type,
                         )
                     )
diff --git a/py/plugins/google-genai/src/genkit/plugins/google_genai/models/utils.py b/py/plugins/google-genai/src/genkit/plugins/google_genai/models/utils.py
index 2940a8983a..7cb69c03bb 100644
--- a/py/plugins/google-genai/src/genkit/plugins/google_genai/models/utils.py
+++ b/py/plugins/google-genai/src/genkit/plugins/google_genai/models/utils.py
@@ -89,10 +89,13 @@ def to_gemini(cls, part: Part) -> genai.types.Part:
                 )
             )
         if isinstance(part.root, MediaPart):
+            url = part.root.media.url
+            if not url.startswith(cls.DATA):
+                raise ValueError(f'Unsupported media URL for inline_data: {url}')
+            data = base64.b64decode(url.split(',', 1)[1])
             return genai.types.Part(
                 inline_data=genai.types.Blob(
-                    data=part.root.media.url,
-                    mime_type=part.root.media.content_type,
+                    data=data,
                 )
             )
         if isinstance(part.root, CustomPart):
@@ -160,9 +163,10 @@ def from_gemini(cls, part: genai.types.Part) -> Part:
                 )
             )
         if part.inline_data:
+            b64_data = base64.b64encode(part.inline_data.data).decode('utf-8')
             return Part(
                 media=Media(
-                    url=base64.b64encode(part.inline_data.data),
+                    url=f'data:{part.inline_data.mime_type};base64,{b64_data}',
                     contentType=part.inline_data.mime_type,
                 )
             )
diff --git a/py/plugins/google-genai/test/models/test_googlegenai_gemini.py b/py/plugins/google-genai/test/models/test_googlegenai_gemini.py
index 6690d6a353..50c05b2b9a 100644
--- a/py/plugins/google-genai/test/models/test_googlegenai_gemini.py
+++ b/py/plugins/google-genai/test/models/test_googlegenai_gemini.py
@@ -14,9 +14,8 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-import base64
 import sys
-import unittest
+import urllib.request
 from unittest.mock import ANY, AsyncMock, MagicMock, patch
 
 if sys.version_info < (3, 11):  # noqa
@@ -186,8 +185,8 @@ async def test_generate_media_response(mocker, version):
 
     assert content.root.media.content_type == response_mimetype
 
-    decoded_url = base64.b64decode(content.root.media.url)
-    assert decoded_url == response_byte_string
+    with urllib.request.urlopen(content.root.media.url) as response:
+        assert response.read() == response_byte_string
 
 
 def test_convert_schema_property(mocker):
diff --git a/py/plugins/google-genai/test/models/test_googlegenai_imagen.py b/py/plugins/google-genai/test/models/test_googlegenai_imagen.py
index a91ee21599..c884389193 100644
--- a/py/plugins/google-genai/test/models/test_googlegenai_imagen.py
+++ b/py/plugins/google-genai/test/models/test_googlegenai_imagen.py
@@ -15,6 +15,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import base64
+import urllib.request
 
 import pytest
 from google import genai
@@ -76,5 +77,5 @@ async def test_generate_media_response(mocker, version):
 
     assert content.root.media.content_type == response_mimetype
 
-    decoded_url = base64.b64decode(content.root.media.url)
-    assert decoded_url == response_byte_string
+    with urllib.request.urlopen(content.root.media.url) as response:
+        assert response.read() == response_byte_string
diff --git a/py/samples/google-genai-hello/src/google_genai_hello.py b/py/samples/google-genai-hello/src/google_genai_hello.py
index b504fdbb4a..2c8da83e98 100644
--- a/py/samples/google-genai-hello/src/google_genai_hello.py
+++ b/py/samples/google-genai-hello/src/google_genai_hello.py
@@ -116,7 +116,6 @@ async def simple_generate_with_tools_flow(value: int, ctx: ActionRunContext) ->
         The generated response with a function.
     """
     response = await ai.generate(
-        model='googleai/gemini-2.5-flash',
         prompt=f'what is a gablorken of {value}',
         tools=['gablorkenTool'],
         on_chunk=ctx.send_chunk,
@@ -149,7 +148,6 @@ async def simple_generate_with_interrupts(value: int) -> str:
         The generated response with a function.
     """
     response1 = await ai.generate(
-        model='googleai/gemini-2.5-flash',
         messages=[
             Message(
                 role=Role.USER,
@@ -164,7 +162,6 @@ async def simple_generate_with_interrupts(value: int) -> str:
 
     tr = tool_response(response1.interrupts[0], 178)
     response = await ai.generate(
-        model='googleai/gemini-2.5-flash',
         messages=response1.messages,
         tool_responses=[tr],
         tools=['gablorkenTool'],