diff --git a/tests/test_inputs.py b/tests/test_inputs.py
index c4339827de8b..0821de3f803a 100644
--- a/tests/test_inputs.py
+++ b/tests/test_inputs.py
@@ -34,6 +34,13 @@
 ]
 
 
+# Test that a nested mixed-type list of lists raises a TypeError.
+@pytest.mark.parametrize("invalid_input", [[[1, 2], ["foo", "bar"]]])
+def test_invalid_input_raise_type_error(invalid_input):
+    with pytest.raises(TypeError):
+        parse_raw_prompts(invalid_input)
+
+
 def test_parse_raw_single_batch_empty():
     with pytest.raises(ValueError, match="at least one prompt"):
         parse_raw_prompts([])
diff --git a/vllm/inputs/parse.py b/vllm/inputs/parse.py
index 211551be8e60..71289277eb98 100644
--- a/vllm/inputs/parse.py
+++ b/vllm/inputs/parse.py
@@ -33,22 +33,31 @@ def parse_raw_prompts(
         if len(prompt) == 0:
             raise ValueError("please provide at least one prompt")
 
+        # case 2: array of strings
         if is_list_of(prompt, str):
-            # case 2: array of strings
             prompt = cast(list[str], prompt)
             return [TextPrompt(prompt=elem) for elem in prompt]
+
+        # case 3: array of tokens
         if is_list_of(prompt, int):
-            # case 3: array of tokens
             prompt = cast(list[int], prompt)
             return [TokensPrompt(prompt_token_ids=prompt)]
+
+        # case 4: array of token arrays
         if is_list_of(prompt, list):
-            prompt = cast(list[list[int]], prompt)
-            if len(prompt[0]) == 0:
-                raise ValueError("please provide at least one prompt")
+            first = prompt[0]
+            if not isinstance(first, list):
+                raise ValueError("prompt expected to be a list of lists")
 
-            if is_list_of(prompt[0], int):
-                # case 4: array of token arrays
-                return [TokensPrompt(prompt_token_ids=elem) for elem in prompt]
+            if len(first) == 0:
+                raise ValueError("Please provide at least one prompt")
+
+            # strict validation: every nested list must be list[int]
+            if not all(is_list_of(elem, int) for elem in prompt):
+                raise TypeError("Nested lists must contain only integers")
+
+            prompt = cast(list[list[int]], prompt)
+            return [TokensPrompt(prompt_token_ids=elem) for elem in prompt]
 
     raise TypeError(
         "prompt must be a string, array of strings, "