diff --git a/api/core/workflow/nodes/trigger_webhook/entities.py b/api/core/workflow/nodes/trigger_webhook/entities.py
index 27e8f69664..2c05fe2298 100644
--- a/api/core/workflow/nodes/trigger_webhook/entities.py
+++ b/api/core/workflow/nodes/trigger_webhook/entities.py
@@ -2,7 +2,7 @@ from collections.abc import Sequence
 from enum import StrEnum
 from typing import Literal, Optional
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 from core.workflow.nodes.base import BaseNodeData
 
@@ -53,6 +53,14 @@ class WebhookData(BaseNodeData):
     params: Sequence[WebhookParameter] = Field(default_factory=list)  # query parameters
     body: Sequence[WebhookBodyParameter] = Field(default_factory=list)
 
+    @field_validator("method", mode="before")
+    @classmethod
+    def normalize_method(cls, v) -> str:
+        """Normalize HTTP method to lowercase to support both uppercase and lowercase input."""
+        if isinstance(v, str):
+            return v.lower()
+        return v
+
     status_code: int = 200  # Expected status code for response
     response_body: str = ""  # Template for response body