diff --git a/esphome/components/wifi/wifi_component_esp_idf.cpp b/esphome/components/wifi/wifi_component_esp_idf.cpp
index 2cbebdc967..ed2fdafba8 100644
--- a/esphome/components/wifi/wifi_component_esp_idf.cpp
+++ b/esphome/components/wifi/wifi_component_esp_idf.cpp
@@ -981,7 +981,8 @@ bool WiFiComponent::wifi_ap_ip_config_(const optional<ManualIP> &manual_ip) {
   // Configure DHCP Option 114 (Captive Portal URI) if captive portal is enabled
   // This provides a standards-compliant way for clients to discover the captive portal
   if (captive_portal::global_captive_portal != nullptr) {
-    char captive_portal_uri[7 + network::IP_ADDRESS_BUFFER_SIZE];  // "http://" + IP
+    // Buffer must be static - dhcps_set_option_info stores pointer, doesn't copy
+    static char captive_portal_uri[7 + network::IP_ADDRESS_BUFFER_SIZE];  // "http://" + IP
     memcpy(captive_portal_uri, "http://", 7);
     network::IPAddress(&info.ip).str_to(captive_portal_uri + 7);
     err = esp_netif_dhcps_option(s_ap_netif, ESP_NETIF_OP_SET, ESP_NETIF_CAPTIVEPORTAL_URI, captive_portal_uri,