diff --git a/vllm/model_executor/models/qwen2_5_omni_thinker.py b/vllm/model_executor/models/qwen2_5_omni_thinker.py
index 00382cf0a8..a0e9b84f34 100644
--- a/vllm/model_executor/models/qwen2_5_omni_thinker.py
+++ b/vllm/model_executor/models/qwen2_5_omni_thinker.py
@@ -509,6 +509,23 @@ class Qwen2_5OmniThinkerMultiModalProcessor(
                 **mm_kwargs,
             )
 
+        merged = self.info.ctx.get_merged_mm_kwargs(mm_kwargs)
+        if mm_data.get("videos") and (
+            merged.keys() & {"size", "min_pixels", "max_pixels"}
+        ):
+            mm_kwargs = dict(mm_kwargs)
+            video_size = dict(self.info.get_hf_processor().video_processor.size)
+            size_override = merged.get("size")
+            if size_override is not None:
+                video_size = video_size | size_override
+            min_pixels = merged.get("min_pixels")
+            if min_pixels is not None:
+                video_size["shortest_edge"] = min_pixels
+            max_pixels = merged.get("max_pixels")
+            if max_pixels is not None:
+                video_size["longest_edge"] = max_pixels
+            mm_kwargs["size"] = video_size
+
         hf_inputs = super()._call_hf_processor(
             prompt=prompt,
             mm_data=mm_data,
diff --git a/vllm/model_executor/models/qwen3_vl.py b/vllm/model_executor/models/qwen3_vl.py
index 5252afd78e..f86560e5f4 100644
--- a/vllm/model_executor/models/qwen3_vl.py
+++ b/vllm/model_executor/models/qwen3_vl.py
@@ -1272,6 +1272,19 @@ class Qwen3VLMultiModalProcessor(BaseMultiModalProcessor[Qwen3VLProcessingInfo])
                 # NOTE: a copy of is created to update do_sample_frames,
                 # otherwise mm_hash for the object will be incorrect.
                 video_mm_kwargs = dict(**mm_kwargs)
+                merged = self.info.ctx.get_merged_mm_kwargs(mm_kwargs)
+                if merged.keys() & {"size", "min_pixels", "max_pixels"}:
+                    video_size = dict(self.info.get_video_processor().size)
+                    size_override = merged.get("size")
+                    if size_override is not None:
+                        video_size = video_size | size_override
+                    min_pixels = merged.get("min_pixels")
+                    if min_pixels is not None:
+                        video_size["shortest_edge"] = min_pixels
+                    max_pixels = merged.get("max_pixels")
+                    if max_pixels is not None:
+                        video_size["longest_edge"] = max_pixels
+                    video_mm_kwargs["size"] = video_size
                 sampled_fps = video_mm_kwargs.get("fps")
                 if is_list_of(sampled_fps, float):
                     video_mm_kwargs["fps"] = sampled_fps[item_idx]