diff --git a/tests/platforms/test_tpu.py b/tests/platforms/test_tpu.py
new file mode 100644
index 000000000000..00776b90e699
--- /dev/null
+++ b/tests/platforms/test_tpu.py
@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: Apache-2.0
+"""Tests for the Pallas MOE implementation.
+
+Run `pytest tests/platforms/test_tpu.py`.
+"""
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+import vllm.config
+from vllm.platforms.tpu import TpuPlatform
+
+
+@pytest.mark.parametrize(
+    "use_v1,initial_block_size,expected_block_size",
+    [
+        (True, 32, 32),  # Case 1: v1: block_size set, should remain unchanged
+        (
+            True, None, 128
+        ),  # Case 2: v1: block_size None, should be set to get_page_size (128)
+        (False, None, 16),  # Case 3: v0: block_size None, should be set to 16
+        (False, 32, 32),  # Case 4: v0: block_size set, should remain unchanged
+    ])
+@patch(
+    "vllm.v1.attention.backends.pallas.PallasAttentionBackend.get_page_size",
+    return_value=128)
+@patch(
+    "vllm.v1.attention.backends.pallas.PallasAttentionBackend.get_min_page_size",
+    return_value=8)
+def test_tpu_platform_update_vllm_config_block_size_respect_passin_block_size(
+        mock_get_min_page_size, mock_get_page_size, use_v1, initial_block_size,
+        expected_block_size) -> None:
+    """Test TPU platform updates VLLM config with block size."""
+    # arrange
+    mock_cached_config = MagicMock()
+    mock_cached_config.block_size = initial_block_size
+
+    mock_model_config = MagicMock()
+    mock_model_config.dtype = "float16"
+
+    mock_vllm_config = MagicMock()
+    mock_vllm_config.cache_config = mock_cached_config
+    mock_vllm_config.compilation_config = MagicMock()
+    mock_vllm_config.compilation_config.level = (
+        vllm.config.CompilationLevel.DYNAMO_ONCE)
+    mock_vllm_config.compilation_config.backend = "openxla"
+    mock_vllm_config.model_config = mock_model_config
+    mock_vllm_config.speculative_config = None
+    mock_vllm_config.parallel_config = MagicMock()
+    mock_vllm_config.parallel_config.worker_cls = (
+        "vllm.v1.worker.tpu_worker.TPUWorker")
+    mock_vllm_config.scheduler_config = MagicMock()
+
+    # act
+    with patch("vllm.envs.VLLM_USE_V1", use_v1):
+        TpuPlatform.check_and_update_config(mock_vllm_config)
+
+    # assert
+    assert mock_cached_config.block_size == expected_block_size
+    if use_v1:
+        mock_get_min_page_size.assert_called()
+        if initial_block_size is None:
+            mock_get_page_size.assert_called()
+        else:
+            mock_get_page_size.assert_not_called()
diff --git a/vllm/platforms/tpu.py b/vllm/platforms/tpu.py
index 41ed94fb619e..0024a948988d 100644
--- a/vllm/platforms/tpu.py
+++ b/vllm/platforms/tpu.py
@@ -93,9 +93,8 @@ def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
         from vllm.config import CompilationLevel
 
         cache_config = vllm_config.cache_config
-        # For v0, the default block size is 16.
-        if cache_config and cache_config.block_size is None:
-            cache_config.block_size = cast(BlockSize, 16)
+        assert cache_config is not None
+
         compilation_config = vllm_config.compilation_config
 
         # TPU only supports DYNAMO_ONCE compilation level
@@ -118,8 +117,14 @@ def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
         if envs.VLLM_USE_V1:
             from vllm.v1.attention.backends.pallas import (
                 PallasAttentionBackend)
-            cache_config.block_size = PallasAttentionBackend.get_page_size(
-                vllm_config)  # type: ignore[assignment]
+
+            # For v1, the default block size is calculated from vllm_config.
+            cache_config.block_size = (
+                cache_config.block_size
+                or PallasAttentionBackend.get_page_size(
+                    vllm_config)  # type: ignore[assignment]
+            )
+
             min_page_size = PallasAttentionBackend.get_min_page_size(
                 vllm_config)
             if min_page_size > cache_config.block_size:
@@ -130,7 +135,10 @@ def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
                     min_page_size,
                 )
                 cache_config.block_size = min_page_size  # type: ignore[assignment]
-
+        else:
+            # For v0, the default block size is 16.
+            cache_config.block_size = (cache_config.block_size
+                                       or cast(BlockSize, 16))
         parallel_config = vllm_config.parallel_config
         scheduler_config = vllm_config.scheduler_config
         if parallel_config.worker_cls == "auto":