diff --git a/esphome/components/mdns/mdns_component.cpp b/esphome/components/mdns/mdns_component.cpp
index eed2516c6a..3a97951d60 100644
--- a/esphome/components/mdns/mdns_component.cpp
+++ b/esphome/components/mdns/mdns_component.cpp
@@ -193,7 +193,7 @@ void MDNSComponent::dump_config() {
     ESP_LOGV(TAG, "  - %s, %s, %d", service.service_type.c_str(), service.proto.c_str(),
              const_cast<TemplatableValue<uint16_t> &>(service.port).value());
     for (const auto &record : service.txt_records) {
-      ESP_LOGV(TAG, "    TXT: %s = %s", record.key.c_str(),
+      ESP_LOGV(TAG, "    TXT: %s = %s", record.key,
                const_cast<TemplatableValue<std::string> &>(record.value).value().c_str());
     }
   }
diff --git a/esphome/components/mdns/mdns_component.h b/esphome/components/mdns/mdns_component.h
index e0e268c914..89cd5db48b 100644
--- a/esphome/components/mdns/mdns_component.h
+++ b/esphome/components/mdns/mdns_component.h
@@ -13,7 +13,7 @@ namespace mdns {
 // MDNS_SERVICE_COUNT will always be defined
 
 struct MDNSTXTRecord {
-  std::string key;
+  const char *key;
   TemplatableValue<std::string> value;
 };
 
diff --git a/esphome/components/mdns/mdns_esp32.cpp b/esphome/components/mdns/mdns_esp32.cpp
index b03455ea2f..85738814c1 100644
--- a/esphome/components/mdns/mdns_esp32.cpp
+++ b/esphome/components/mdns/mdns_esp32.cpp
@@ -29,8 +29,8 @@ void MDNSComponent::setup() {
     std::vector<mdns_txt_item_t> txt_records;
     for (const auto &record : service.txt_records) {
       mdns_txt_item_t it{};
-      // key is a persistent string in services_, no need to strdup
-      it.key = record.key.c_str();
+      // key is a compile-time string literal in flash, no need to strdup
+      it.key = record.key;
       // value is a temporary from TemplatableValue, must strdup to keep it alive
       it.value = strdup(const_cast<TemplatableValue<std::string> &>(record.value).value().c_str());
       txt_records.push_back(it);
diff --git a/esphome/components/mdns/mdns_esp8266.cpp b/esphome/components/mdns/mdns_esp8266.cpp
index 2c90d57021..3be75263f2 100644
--- a/esphome/components/mdns/mdns_esp8266.cpp
+++ b/esphome/components/mdns/mdns_esp8266.cpp
@@ -32,7 +32,7 @@ void MDNSComponent::setup() {
     uint16_t port = const_cast<TemplatableValue<uint16_t> &>(service.port).value();
     MDNS.addService(service_type, proto, port);
     for (const auto &record : service.txt_records) {
-      MDNS.addServiceTxt(service_type, proto, record.key.c_str(),
+      MDNS.addServiceTxt(service_type, proto, record.key,
                          const_cast<TemplatableValue<std::string> &>(record.value).value().c_str());
     }
   }
diff --git a/esphome/components/mdns/mdns_libretiny.cpp b/esphome/components/mdns/mdns_libretiny.cpp
index 7a41ec9dce..e779e563c5 100644
--- a/esphome/components/mdns/mdns_libretiny.cpp
+++ b/esphome/components/mdns/mdns_libretiny.cpp
@@ -32,7 +32,7 @@ void MDNSComponent::setup() {
     uint16_t port_ = const_cast<TemplatableValue<uint16_t> &>(service.port).value();
     MDNS.addService(service_type, proto, port_);
     for (const auto &record : service.txt_records) {
-      MDNS.addServiceTxt(service_type, proto, record.key.c_str(),
+      MDNS.addServiceTxt(service_type, proto, record.key,
                          const_cast<TemplatableValue<std::string> &>(record.value).value().c_str());
     }
   }
diff --git a/esphome/components/mdns/mdns_rp2040.cpp b/esphome/components/mdns/mdns_rp2040.cpp
index 95894323f4..66fda3e261 100644
--- a/esphome/components/mdns/mdns_rp2040.cpp
+++ b/esphome/components/mdns/mdns_rp2040.cpp
@@ -32,7 +32,7 @@ void MDNSComponent::setup() {
     uint16_t port = const_cast<TemplatableValue<uint16_t> &>(service.port).value();
     MDNS.addService(service_type, proto, port);
     for (const auto &record : service.txt_records) {
-      MDNS.addServiceTxt(service_type, proto, record.key.c_str(),
+      MDNS.addServiceTxt(service_type, proto, record.key,
                          const_cast<TemplatableValue<std::string> &>(record.value).value().c_str());
     }
   }
diff --git a/esphome/components/openthread/openthread.cpp b/esphome/components/openthread/openthread.cpp
index 57b972d195..d1fe677a93 100644
--- a/esphome/components/openthread/openthread.cpp
+++ b/esphome/components/openthread/openthread.cpp
@@ -181,7 +181,7 @@ void OpenThreadSrpComponent::setup() {
     for (size_t i = 0; i < service.txt_records.size(); i++) {
       const auto &txt = service.txt_records[i];
       auto value = const_cast<TemplatableValue<std::string> &>(txt.value).value();
-      txt_entries[i].mKey = strdup(txt.key.c_str());
+      txt_entries[i].mKey = txt.key;  // Compile-time string literal in flash
       txt_entries[i].mValue = reinterpret_cast<const uint8_t *>(strdup(value.c_str()));
       txt_entries[i].mValueLength = value.size();
     }