diff --git a/esphome/components/web_server_idf/__init__.py b/esphome/components/web_server_idf/__init__.py
index adf21ddc49..1f195425f5 100644
--- a/esphome/components/web_server_idf/__init__.py
+++ b/esphome/components/web_server_idf/__init__.py
@@ -2,6 +2,7 @@ from esphome.components.esp32 import (
     add_idf_sdkconfig_option,
     include_builtin_idf_component,
 )
+from esphome.config_helpers import filter_source_files_from_defines
 import esphome.config_validation as cv
 
 CODEOWNERS = ["@dentra"]
@@ -18,3 +19,10 @@ async def to_code(config):
     # Re-enable esp-tls (excluded by default to save compile time);
     # web_server_idf.cpp includes <esp_tls_crypto.h> for digest auth
     include_builtin_idf_component("esp-tls")
+
+
+# multipart.cpp is fully #ifdef'd on USE_WEBSERVER_OTA (set by the
+# web_server OTA platform); skip it when OTA uploads are not configured.
+FILTER_SOURCE_FILES = filter_source_files_from_defines(
+    {"multipart.cpp": "USE_WEBSERVER_OTA"}
+)