Happy birthday, Prince George!

Duchess Kate Middleton and Prince William's son George is four years old today and the royal family has shared this commemorative photo with the world -- and royal watchers are calling George the cutest human being ever to walk the earth!

Okay, maybe they're not quite that obsessed, but we are! The little tyke smiled from ear-to-ear for his birthday pic, which Buckingham Palace posted Friday with this message: "The Duke and Duchess are delighted to share a new official portrait of Prince George to mark His Royal Highness's fourth birthday tomorrow 🎈"

The entire family just returned from a trip to Poland and Germany where George and his little sister Charlotte were, as always, the focus of attention. They're international superstars!