diff --git a/vllm/entrypoints/generate/beam_search/offline.py b/vllm/entrypoints/generate/beam_search/offline.py
index e1bceb5d23..7814d4d44e 100644
--- a/vllm/entrypoints/generate/beam_search/offline.py
+++ b/vllm/entrypoints/generate/beam_search/offline.py
@@ -119,6 +119,7 @@ class BeamSearchOfflineMixin(OfflineInferenceMixin):
             logprobs=2 * beam_width,
             max_tokens=1,
             temperature=temperature,
+            detokenize=False,
             skip_clone=True,  # Internal beam search, safe to skip clone
         )
         instances: list[BeamSearchInstance] = []
@@ -443,6 +444,7 @@ class BeamSearchOfflineMixin(OfflineInferenceMixin):
                 logprobs=base_params.logprobs,
                 max_tokens=1,
                 temperature=base_params.temperature,
+                detokenize=False,
                 allowed_token_ids=(
                     allowed_ids
                     if len(allowed_ids) <= _MAX_NUM_ALLOWED_TOKEN_IDS