We know, we can't believe he's two already either!
It feels like just the other day that author and designer Coleen gave birth to the couple's second child, Klay Anthony Rooney, at Liverpool's Women's Hospital.
Today, he shared a picture of the birthday boy to Twitter, saying: "Happy second birthday to our beautiful boy Klay."
We're guessing Klay is a major Toy Story fan as we spy a very cool, very large inflatable Buzz Lightyear balloon and the little boy is clutching Jessie doll.
Manchester United player Wayne, meanwhile, shared an image to his own Twitter account showing little Klay out on the pitch at Old Trafford.
We wonder what Klay's got for his birthday?!
Meanwhile, in other Rooney family news, Wayne had everyone chuckling over the weekend when he shared a video to Instagram showing Klay's big brother Kai, five, merrily signing autographs!
Wayne told fans he'd left the football ground with his young son and stopped to sign autographs. When he glanced over his shoulder he saw the little boy doing the exact same thing!
Watch the cute moment below!