diff --git a/esphome/components/ble_client/automation.h b/esphome/components/ble_client/automation.h
index a5c661e2f5..55f1cb2f46 100644
--- a/esphome/components/ble_client/automation.h
+++ b/esphome/components/ble_client/automation.h
@@ -96,8 +96,11 @@ template<typename... Ts> class BLEClientWriteAction : public Action<Ts...>, publ
   BLEClientWriteAction(BLEClient *ble_client) {
     ble_client->register_ble_node(this);
     ble_client_ = ble_client;
+    this->construct_simple_value_();
   }
 
+  ~BLEClientWriteAction() { this->destroy_simple_value_(); }
+
   void set_service_uuid16(uint16_t uuid) { this->service_uuid_ = espbt::ESPBTUUID::from_uint16(uuid); }
   void set_service_uuid32(uint32_t uuid) { this->service_uuid_ = espbt::ESPBTUUID::from_uint32(uuid); }
   void set_service_uuid128(uint8_t *uuid) { this->service_uuid_ = espbt::ESPBTUUID::from_raw(uuid); }
@@ -106,14 +109,18 @@ template<typename... Ts> class BLEClientWriteAction : public Action<Ts...>, publ
   void set_char_uuid32(uint32_t uuid) { this->char_uuid_ = espbt::ESPBTUUID::from_uint32(uuid); }
   void set_char_uuid128(uint8_t *uuid) { this->char_uuid_ = espbt::ESPBTUUID::from_raw(uuid); }
 
-  void set_value_template(std::function<std::vector<uint8_t>(Ts...)> func) {
-    this->value_template_ = std::move(func);
-    has_simple_value_ = false;
+  void set_value_template(std::vector<uint8_t> (*func)(Ts...)) {
+    this->destroy_simple_value_();
+    this->value_.template_func = func;
+    this->has_simple_value_ = false;
   }
 
   void set_value_simple(const std::vector<uint8_t> &value) {
-    this->value_simple_ = value;
-    has_simple_value_ = true;
+    if (!this->has_simple_value_) {
+      this->construct_simple_value_();
+    }
+    this->value_.simple = value;
+    this->has_simple_value_ = true;
   }
 
   void play(Ts... x) override {}
@@ -121,7 +128,7 @@ template<typename... Ts> class BLEClientWriteAction : public Action<Ts...>, publ
   void play_complex(Ts... x) override {
     this->num_running_++;
     this->var_ = std::make_tuple(x...);
-    auto value = this->has_simple_value_ ? this->value_simple_ : this->value_template_(x...);
+    auto value = this->has_simple_value_ ? this->value_.simple : this->value_.template_func(x...);
     // on write failure, continue the automation chain rather than stopping so that e.g. disconnect can work.
     if (!write(value))
       this->play_next_(x...);
@@ -194,10 +201,22 @@ template<typename... Ts> class BLEClientWriteAction : public Action<Ts...>, publ
   }
 
  private:
+  void construct_simple_value_() { new (&this->value_.simple) std::vector<uint8_t>(); }
+
+  void destroy_simple_value_() {
+    if (this->has_simple_value_) {
+      this->value_.simple.~vector();
+    }
+  }
+
   BLEClient *ble_client_;
   bool has_simple_value_ = true;
-  std::vector<uint8_t> value_simple_;
-  std::function<std::vector<uint8_t>(Ts...)> value_template_{};
+  union Value {
+    std::vector<uint8_t> simple;
+    std::vector<uint8_t> (*template_func)(Ts...);
+    Value() {}   // trivial constructor
+    ~Value() {}  // trivial destructor - we manage lifetime via discriminator
+  } value_;
   espbt::ESPBTUUID service_uuid_;
   espbt::ESPBTUUID char_uuid_;
   std::tuple<Ts...> var_{};
@@ -213,9 +232,9 @@ template<typename... Ts> class BLEClientPasskeyReplyAction : public Action<Ts...
   void play(Ts... x) override {
     uint32_t passkey;
     if (has_simple_value_) {
-      passkey = this->value_simple_;
+      passkey = this->value_.simple;
     } else {
-      passkey = this->value_template_(x...);
+      passkey = this->value_.template_func(x...);
     }
     if (passkey > 999999)
       return;
@@ -224,21 +243,23 @@ template<typename... Ts> class BLEClientPasskeyReplyAction : public Action<Ts...
     esp_ble_passkey_reply(remote_bda, true, passkey);
   }
 
-  void set_value_template(std::function<uint32_t(Ts...)> func) {
-    this->value_template_ = std::move(func);
-    has_simple_value_ = false;
+  void set_value_template(uint32_t (*func)(Ts...)) {
+    this->value_.template_func = func;
+    this->has_simple_value_ = false;
   }
 
   void set_value_simple(const uint32_t &value) {
-    this->value_simple_ = value;
-    has_simple_value_ = true;
+    this->value_.simple = value;
+    this->has_simple_value_ = true;
   }
 
  private:
   BLEClient *parent_{nullptr};
   bool has_simple_value_ = true;
-  uint32_t value_simple_{0};
-  std::function<uint32_t(Ts...)> value_template_{};
+  union {
+    uint32_t simple;
+    uint32_t (*template_func)(Ts...);
+  } value_{.simple = 0};
 };
 
 template<typename... Ts> class BLEClientNumericComparisonReplyAction : public Action<Ts...> {
@@ -249,27 +270,29 @@ template<typename... Ts> class BLEClientNumericComparisonReplyAction : public Ac
     esp_bd_addr_t remote_bda;
     memcpy(remote_bda, parent_->get_remote_bda(), sizeof(esp_bd_addr_t));
     if (has_simple_value_) {
-      esp_ble_confirm_reply(remote_bda, this->value_simple_);
+      esp_ble_confirm_reply(remote_bda, this->value_.simple);
     } else {
-      esp_ble_confirm_reply(remote_bda, this->value_template_(x...));
+      esp_ble_confirm_reply(remote_bda, this->value_.template_func(x...));
     }
   }
 
-  void set_value_template(std::function<bool(Ts...)> func) {
-    this->value_template_ = std::move(func);
-    has_simple_value_ = false;
+  void set_value_template(bool (*func)(Ts...)) {
+    this->value_.template_func = func;
+    this->has_simple_value_ = false;
   }
 
   void set_value_simple(const bool &value) {
-    this->value_simple_ = value;
-    has_simple_value_ = true;
+    this->value_.simple = value;
+    this->has_simple_value_ = true;
   }
 
  private:
   BLEClient *parent_{nullptr};
   bool has_simple_value_ = true;
-  bool value_simple_{false};
-  std::function<bool(Ts...)> value_template_{};
+  union {
+    bool simple;
+    bool (*template_func)(Ts...);
+  } value_{.simple = false};
 };
 
 template<typename... Ts> class BLEClientRemoveBondAction : public Action<Ts...> {
diff --git a/esphome/components/ble_client/sensor/ble_sensor.cpp b/esphome/components/ble_client/sensor/ble_sensor.cpp
index d0ccfe1f2e..6d293528c6 100644
--- a/esphome/components/ble_client/sensor/ble_sensor.cpp
+++ b/esphome/components/ble_client/sensor/ble_sensor.cpp
@@ -117,9 +117,9 @@ void BLESensor::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t ga
 }
 
 float BLESensor::parse_data_(uint8_t *value, uint16_t value_len) {
-  if (this->data_to_value_func_.has_value()) {
+  if (this->has_data_to_value_) {
     std::vector<uint8_t> data(value, value + value_len);
-    return (*this->data_to_value_func_)(data);
+    return this->data_to_value_func_(data);
   } else {
     return value[0];
   }
diff --git a/esphome/components/ble_client/sensor/ble_sensor.h b/esphome/components/ble_client/sensor/ble_sensor.h
index 24d1ed2fd2..c6335d5836 100644
--- a/esphome/components/ble_client/sensor/ble_sensor.h
+++ b/esphome/components/ble_client/sensor/ble_sensor.h
@@ -15,8 +15,6 @@ namespace ble_client {
 
 namespace espbt = esphome::esp32_ble_tracker;
 
-using data_to_value_t = std::function<float(std::vector<uint8_t>)>;
-
 class BLESensor : public sensor::Sensor, public PollingComponent, public BLEClientNode {
  public:
   void loop() override;
@@ -33,13 +31,17 @@ class BLESensor : public sensor::Sensor, public PollingComponent, public BLEClie
   void set_descr_uuid16(uint16_t uuid) { this->descr_uuid_ = espbt::ESPBTUUID::from_uint16(uuid); }
   void set_descr_uuid32(uint32_t uuid) { this->descr_uuid_ = espbt::ESPBTUUID::from_uint32(uuid); }
   void set_descr_uuid128(uint8_t *uuid) { this->descr_uuid_ = espbt::ESPBTUUID::from_raw(uuid); }
-  void set_data_to_value(data_to_value_t &&lambda) { this->data_to_value_func_ = lambda; }
+  void set_data_to_value(float (*lambda)(const std::vector<uint8_t> &)) {
+    this->data_to_value_func_ = lambda;
+    this->has_data_to_value_ = true;
+  }
   void set_enable_notify(bool notify) { this->notify_ = notify; }
   uint16_t handle;
 
  protected:
   float parse_data_(uint8_t *value, uint16_t value_len);
-  optional<data_to_value_t> data_to_value_func_{};
+  bool has_data_to_value_{false};
+  float (*data_to_value_func_)(const std::vector<uint8_t> &){};
   bool notify_;
   espbt::ESPBTUUID service_uuid_;
   espbt::ESPBTUUID char_uuid_;