diff --git a/esphome/components/captive_portal/captive_portal.cpp b/esphome/components/captive_portal/captive_portal.cpp
index 8d88a10b27..95f7863102 100644
--- a/esphome/components/captive_portal/captive_portal.cpp
+++ b/esphome/components/captive_portal/captive_portal.cpp
@@ -47,8 +47,8 @@ void CaptivePortal::handle_config(AsyncWebServerRequest *request) {
   request->send(stream);
 }
 void CaptivePortal::handle_wifisave(AsyncWebServerRequest *request) {
-  std::string ssid = request->arg("ssid").c_str();  // NOLINT(readability-redundant-string-cstr)
-  std::string psk = request->arg("psk").c_str();    // NOLINT(readability-redundant-string-cstr)
+  const auto &ssid = request->arg("ssid");
+  const auto &psk = request->arg("psk");
   ESP_LOGI(TAG,
            "Requested WiFi Settings Change:\n"
            "  SSID='%s'\n"
@@ -56,10 +56,12 @@ void CaptivePortal::handle_wifisave(AsyncWebServerRequest *request) {
            ssid.c_str(), psk.c_str());
 #ifdef USE_ESP8266
   // ESP8266 is single-threaded, call directly
-  wifi::global_wifi_component->save_wifi_sta(ssid, psk);
+  wifi::global_wifi_component->save_wifi_sta(ssid.c_str(), psk.c_str());
 #else
   // Defer save to main loop thread to avoid NVS operations from HTTP thread
-  this->defer([ssid, psk]() { wifi::global_wifi_component->save_wifi_sta(ssid, psk); });
+  this->defer([ssid = std::string(ssid.c_str(), ssid.length()), psk = std::string(psk.c_str(), psk.length())]() {
+    wifi::global_wifi_component->save_wifi_sta(ssid, psk);
+  });
 #endif
   request->redirect(ESPHOME_F("/?save"));
 }