diff --git a/esphome/core/automation.h b/esphome/core/automation.h
index 355968b284..7a054f9899 100644
--- a/esphome/core/automation.h
+++ b/esphome/core/automation.h
@@ -54,6 +54,9 @@ template<typename T, typename... X> class TemplatableFn {
       std::invocable<F, X...> &&std::convertible_to<std::invoke_result_t<F, X...>, T> &&std::is_empty_v<F>
           &&std::default_initializable<F> : f_([](X... x) -> T { return static_cast<T>(F{}(x...)); }) {}
 
+  // Reject stateful lambdas (non-empty, i.e. capturing) with a clear error
+  template<typename F> TemplatableFn(F) requires std::invocable<F, X...> &&(!std::is_empty_v<F>) = delete;
+
   bool has_value() const { return this->f_ != nullptr; }
 
   T value(X... x) const { return this->f_ ? this->f_(x...) : T{}; }