diff --git a/ci_cd/generate_model_prices_schema.py b/ci_cd/generate_model_prices_schema.py
index ab29b70bdd4..bf669ccce29 100644
--- a/ci_cd/generate_model_prices_schema.py
+++ b/ci_cd/generate_model_prices_schema.py
@@ -31,7 +31,45 @@ EXTRA_BOOLEAN_KEYS = frozenset(
     }
 )
 
+HOURS_UTC: JsonSchema = {
+    "description": 'UTC "HH:MM-HH:MM" window, or a list of them; a window may wrap past midnight.',
+    "oneOf": [STRING, {"type": "array", "items": STRING, "minItems": 1}],
+}
+
+OFF_PEAK_WINDOW: JsonSchema = {
+    "type": "object",
+    "properties": {
+        "hours_utc": HOURS_UTC,
+        "weekdays": {
+            "type": "array",
+            "description": "ISO-8601 weekday numbers (1 = Monday .. 7 = Sunday) or English day names the window applies on.",
+            "items": {"oneOf": [{"type": "integer", "minimum": 1, "maximum": 7}, STRING]},
+            "minItems": 1,
+        },
+    },
+    "required": ["hours_utc"],
+    "additionalProperties": False,
+}
+
 OBJECT_KEYS: dict[str, JsonSchema] = {
+    "off_peak_pricing": {
+        "type": "object",
+        "description": "Rates that replace the same-named base fields while the request falls inside the stated UTC windows.",
+        "properties": {
+            "hours_utc": HOURS_UTC,
+            "windows": {"type": "array", "items": OFF_PEAK_WINDOW, "minItems": 1},
+            "weekday_timezone": {
+                "type": "string",
+                "description": "IANA zone the weekdays of each window are read on; defaults to UTC.",
+            },
+            "input_cost_per_token": NONNEG_NUMBER,
+            "output_cost_per_token": NONNEG_NUMBER,
+            "output_cost_per_reasoning_token": NONNEG_NUMBER,
+            "cache_read_input_token_cost": NONNEG_NUMBER,
+            "cache_creation_input_token_cost": NONNEG_NUMBER,
+        },
+        "additionalProperties": False,
+    },
     "search_context_cost_per_query": {
         "type": "object",
         "description": "USD cost per web search query, keyed by search context size.",
diff --git a/tests/test_litellm/test_model_prices_schema.py b/tests/test_litellm/test_model_prices_schema.py
index 2f9b11a16b7..65aaa2870ef 100644
--- a/tests/test_litellm/test_model_prices_schema.py
+++ b/tests/test_litellm/test_model_prices_schema.py
@@ -125,6 +125,50 @@ def test_schema_accepts_cache_creation_cost_inside_a_pricing_tier(committed_sche
     assert validator.is_valid({"some-model": entry})
 
 
+OFF_PEAK_ENTRY: Final = MappingProxyType(
+    {
+        "litellm_provider": "openrouter",
+        "mode": "chat",
+        "input_cost_per_token": 2e-6,
+        "output_cost_per_token": 8e-6,
+        "off_peak_pricing": {
+            "hours_utc": "16:30-00:30",
+            "windows": [{"hours_utc": ["00:30-02:00"], "weekdays": [6, "Sunday"]}],
+            "weekday_timezone": "Asia/Shanghai",
+            "input_cost_per_token": 1e-6,
+            "output_cost_per_token": 4e-6,
+            "cache_read_input_token_cost": 1e-7,
+        },
+    }
+)
+
+
+def test_generator_classifies_off_peak_pricing_as_a_windowed_rate_block():
+    generator = load_generator()
+    schema = json.loads(generator.render(generator.build_schema({"some-model": dict(OFF_PEAK_ENTRY)})))
+    validator = build_validator(schema)
+    assert validator.is_valid({"some-model": dict(OFF_PEAK_ENTRY)})
+
+
+@pytest.mark.parametrize(
+    "block",
+    [
+        {"hours_utc": "16:30-00:30", "input_cost_per_token": "1e-6"},
+        {"hours_utc": "16:30-00:30", "input_cost_per_token": -1e-6},
+        {"hours_utc": 1630, "input_cost_per_token": 1e-6},
+        {"hours_utc": "16:30-00:30", "discount": 0.5},
+        {"windows": [{"weekdays": [6]}], "input_cost_per_token": 1e-6},
+        {"windows": [{"hours_utc": "00:30-02:00", "weekdays": [0]}], "input_cost_per_token": 1e-6},
+        {"windows": [], "input_cost_per_token": 1e-6},
+    ],
+)
+def test_generated_off_peak_schema_rejects_malformed_blocks(block: dict):
+    generator = load_generator()
+    schema = json.loads(generator.render(generator.build_schema({"some-model": dict(OFF_PEAK_ENTRY)})))
+    validator = build_validator(schema)
+    assert not validator.is_valid({"some-model": {**OFF_PEAK_ENTRY, "off_peak_pricing": block}})
+
+
 def find_duplicate_keys(path: Path) -> list[str]:
     duplicates: list[str] = []