diff --git a/esphome/components/fan/fan.h b/esphome/components/fan/fan.h
index c16ec389f20..f1b17d7e15d 100644
--- a/esphome/components/fan/fan.h
+++ b/esphome/components/fan/fan.h
@@ -153,6 +153,7 @@ class Fan : public EntityBase {
   void dump_traits_(const char *tag, const char *prefix);
 
   /// Set the preset mode (finds and stores pointer from traits). Returns true if changed.
+  /// Passing nullptr or empty string clears the preset mode.
   bool set_preset_mode_(const char *preset_mode, size_t len);
   bool set_preset_mode_(const char *preset_mode);
   bool set_preset_mode_(const std::string &preset_mode);