diff --git a/litellm/litellm_core_utils/llm_cost_calc/utils.py b/litellm/litellm_core_utils/llm_cost_calc/utils.py
index c968fac254e..b34c416cd40 100644
--- a/litellm/litellm_core_utils/llm_cost_calc/utils.py
+++ b/litellm/litellm_core_utils/llm_cost_calc/utils.py
@@ -443,7 +443,7 @@ def _apply_off_peak_pricing(
     off_peak_pricing falls back to the standard rate.
     """
     off_peak: Final = model_info.get("off_peak_pricing")
-    if not off_peak or not _is_off_peak(off_peak, current_time):
+    if not isinstance(off_peak, Mapping) or not _is_off_peak(off_peak, current_time):
         return prompt_base_cost, completion_base_cost, cache_read_cost
     return (
         _coerce_off_peak_rate(off_peak.get("input_cost_per_token"), prompt_base_cost),
diff --git a/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_llm_cost_calc_utils.py b/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_llm_cost_calc_utils.py
index 501a9314c90..0e1c832ebf5 100644
--- a/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_llm_cost_calc_utils.py
+++ b/tests/test_litellm/litellm_core_utils/llm_cost_calc/test_llm_cost_calc_utils.py
@@ -648,6 +648,33 @@ def test_get_token_base_cost_applies_off_peak_pricing():
     assert peak[4] == 1e-7
 
 
+def test_get_token_base_cost_non_mapping_off_peak_block_bills_standard_rates():
+    """A truthy non-mapping off_peak_pricing value (a bare string or a list in
+    YAML) must bill standard rates rather than raising, matching how every
+    other malformed piece of the block behaves.
+    """
+    from datetime import datetime, timezone
+    from typing import cast
+
+    from litellm.types.utils import ModelInfo
+
+    usage = Usage(prompt_tokens=100, completion_tokens=50, total_tokens=150)
+    when = datetime(2026, 1, 1, 18, 0, tzinfo=timezone.utc)
+
+    for malformed_block in ("16:00-19:00", ["16:00-19:00"], 5e-7, True):
+        model_info = cast(
+            ModelInfo,
+            {
+                "input_cost_per_token": 1e-6,
+                "output_cost_per_token": 2e-6,
+                "off_peak_pricing": malformed_block,
+            },
+        )
+        result = _get_token_base_cost(model_info, usage, current_time=when)
+        assert result[0] == 1e-6
+        assert result[1] == 2e-6
+
+
 def test_get_token_base_cost_off_peak_falls_back_to_standard_when_unset():
     from datetime import datetime, timezone
     from typing import cast