diff --git a/esphome/components/web_server_idf/utils.cpp b/esphome/components/web_server_idf/utils.cpp
index d5d34b520b..f27814062c 100644
--- a/esphome/components/web_server_idf/utils.cpp
+++ b/esphome/components/web_server_idf/utils.cpp
@@ -13,7 +13,8 @@ namespace web_server_idf {
 
 static const char *const TAG = "web_server_idf_utils";
 
-void url_decode(char *str) {
+size_t url_decode(char *str) {
+  char *start = str;
   char *ptr = str, buf;
   for (; *str; str++, ptr++) {
     if (*str == '%') {
@@ -31,7 +32,8 @@ void url_decode(char *str) {
       *ptr = *str;
     }
   }
-  *ptr = *str;
+  *ptr = '\0';
+  return ptr - start;
 }
 
 bool request_has_header(httpd_req_t *req, const char *name) { return httpd_req_get_hdr_value_len(req, name); }
diff --git a/esphome/components/web_server_idf/utils.h b/esphome/components/web_server_idf/utils.h
index f70a5f0760..3a86aec7ac 100644
--- a/esphome/components/web_server_idf/utils.h
+++ b/esphome/components/web_server_idf/utils.h
@@ -8,6 +8,10 @@
 namespace esphome {
 namespace web_server_idf {
 
+/// Decode URL-encoded string in-place (e.g., %20 -> space, + -> space)
+/// Returns the new length of the decoded string
+size_t url_decode(char *str);
+
 bool request_has_header(httpd_req_t *req, const char *name);
 optional<std::string> request_get_header(httpd_req_t *req, const char *name);
 optional<std::string> request_get_url_query(httpd_req_t *req);
diff --git a/esphome/components/web_server_idf/web_server_idf.cpp b/esphome/components/web_server_idf/web_server_idf.cpp
index 3d76b86a14..cb6c86f7eb 100644
--- a/esphome/components/web_server_idf/web_server_idf.cpp
+++ b/esphome/components/web_server_idf/web_server_idf.cpp
@@ -247,11 +247,18 @@ optional<std::string> AsyncWebServerRequest::get_header(const char *name) const
 }
 
 std::string AsyncWebServerRequest::url() const {
-  auto *str = strchr(this->req_->uri, '?');
-  if (str == nullptr) {
-    return this->req_->uri;
+  auto *query_start = strchr(this->req_->uri, '?');
+  std::string result;
+  if (query_start == nullptr) {
+    result = this->req_->uri;
+  } else {
+    result = std::string(this->req_->uri, query_start - this->req_->uri);
   }
-  return std::string(this->req_->uri, str - this->req_->uri);
+  // Decode URL-encoded characters in-place (e.g., %20 -> space)
+  // This matches AsyncWebServer behavior on Arduino
+  size_t new_len = url_decode(&result[0]);
+  result.resize(new_len);
+  return result;
 }
 
 std::string AsyncWebServerRequest::host() const { return this->get_header("Host").value(); }