diff --git a/esphome/components/template/cover/template_cover.cpp b/esphome/components/template/cover/template_cover.cpp
index d5e0967e1e3..93ad887e580 100644
--- a/esphome/components/template/cover/template_cover.cpp
+++ b/esphome/components/template/cover/template_cover.cpp
@@ -53,7 +53,6 @@ void TemplateCover::loop() {
   if (changed)
     this->publish_state();
 }
-void TemplateCover::set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
 void TemplateCover::set_assumed_state(bool assumed_state) { this->assumed_state_ = assumed_state; }
 float TemplateCover::get_setup_priority() const { return setup_priority::HARDWARE; }
 Trigger<> *TemplateCover::get_open_trigger() { return &this->open_trigger_; }
diff --git a/esphome/components/template/cover/template_cover.h b/esphome/components/template/cover/template_cover.h
index 20c092cda79..cca21046202 100644
--- a/esphome/components/template/cover/template_cover.h
+++ b/esphome/components/template/cover/template_cover.h
@@ -25,7 +25,7 @@ class TemplateCover final : public cover::Cover, public Component {
   Trigger<> *get_toggle_trigger();
   Trigger<float> *get_position_trigger();
   Trigger<float> *get_tilt_trigger();
-  void set_optimistic(bool optimistic);
+  void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
   void set_assumed_state(bool assumed_state);
   void set_has_stop(bool has_stop);
   void set_has_position(bool has_position);
diff --git a/esphome/components/template/lock/template_lock.cpp b/esphome/components/template/lock/template_lock.cpp
index 6e73623ae9b..4a293aab858 100644
--- a/esphome/components/template/lock/template_lock.cpp
+++ b/esphome/components/template/lock/template_lock.cpp
@@ -47,7 +47,6 @@ void TemplateLock::open_latch() {
   this->prev_trigger_ = &this->open_trigger_;
   this->open_trigger_.trigger();
 }
-void TemplateLock::set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
 float TemplateLock::get_setup_priority() const { return setup_priority::HARDWARE; }
 void TemplateLock::dump_config() {
   LOG_LOCK("", "Template Lock", this);
diff --git a/esphome/components/template/lock/template_lock.h b/esphome/components/template/lock/template_lock.h
index 03e3e86d88e..9b0a1ffe984 100644
--- a/esphome/components/template/lock/template_lock.h
+++ b/esphome/components/template/lock/template_lock.h
@@ -18,7 +18,7 @@ class TemplateLock final : public lock::Lock, public Component {
   Trigger<> *get_lock_trigger() { return &this->lock_trigger_; }
   Trigger<> *get_unlock_trigger() { return &this->unlock_trigger_; }
   Trigger<> *get_open_trigger() { return &this->open_trigger_; }
-  void set_optimistic(bool optimistic);
+  void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
   void loop() override;
 
   float get_setup_priority() const override;
diff --git a/esphome/components/template/switch/template_switch.cpp b/esphome/components/template/switch/template_switch.cpp
index 05288b2d4e0..27134fc8b29 100644
--- a/esphome/components/template/switch/template_switch.cpp
+++ b/esphome/components/template/switch/template_switch.cpp
@@ -29,7 +29,6 @@ void TemplateSwitch::write_state(bool state) {
   if (this->optimistic_)
     this->publish_state(state);
 }
-void TemplateSwitch::set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
 bool TemplateSwitch::assumed_state() { return this->assumed_state_; }
 float TemplateSwitch::get_setup_priority() const { return setup_priority::HARDWARE - 2.0f; }
 Trigger<> *TemplateSwitch::get_turn_on_trigger() { return &this->turn_on_trigger_; }
diff --git a/esphome/components/template/switch/template_switch.h b/esphome/components/template/switch/template_switch.h
index 3b8b6cde424..9af8517f9ac 100644
--- a/esphome/components/template/switch/template_switch.h
+++ b/esphome/components/template/switch/template_switch.h
@@ -17,7 +17,7 @@ class TemplateSwitch final : public switch_::Switch, public Component {
   template<typename F> void set_state_lambda(F &&f) { this->f_.set(std::forward<F>(f)); }
   Trigger<> *get_turn_on_trigger();
   Trigger<> *get_turn_off_trigger();
-  void set_optimistic(bool optimistic);
+  void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
   void set_assumed_state(bool assumed_state);
   void loop() override;
 
diff --git a/esphome/components/template/valve/template_valve.cpp b/esphome/components/template/valve/template_valve.cpp
index 3ebeec12856..c9aa161b117 100644
--- a/esphome/components/template/valve/template_valve.cpp
+++ b/esphome/components/template/valve/template_valve.cpp
@@ -47,7 +47,6 @@ void TemplateValve::loop() {
     this->publish_state();
 }
 
-void TemplateValve::set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
 void TemplateValve::set_assumed_state(bool assumed_state) { this->assumed_state_ = assumed_state; }
 float TemplateValve::get_setup_priority() const { return setup_priority::HARDWARE; }
 
diff --git a/esphome/components/template/valve/template_valve.h b/esphome/components/template/valve/template_valve.h
index 76c4630aa02..e123f66d7e8 100644
--- a/esphome/components/template/valve/template_valve.h
+++ b/esphome/components/template/valve/template_valve.h
@@ -23,7 +23,7 @@ class TemplateValve final : public valve::Valve, public Component {
   Trigger<> *get_stop_trigger();
   Trigger<> *get_toggle_trigger();
   Trigger<float> *get_position_trigger();
-  void set_optimistic(bool optimistic);
+  void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
   void set_assumed_state(bool assumed_state);
   void set_has_stop(bool has_stop);
   void set_has_position(bool has_position);