Louis announced the arrival of his brand new son on Saturday 23 January.
He told his Twitter followers: "I'm pleased to say my baby son was born yesterday :) He is healthy and pretty amazing :) I'm very happy!!"
It's believed that Louis was by his former flame Briana Jungwirth's side as she gave birth to the star's first child.
He was even spotted wearing a hospital band on his wrist as he nipped into a sunglasses shop in Los Angeles.
And Louis, 24, is obviously thrilled about becoming a dad for the first time.
The One Direction singer Tweeted a headphone emoji and the words "Daddy Cool".
Then, barely able to contain himself, he Tweeted another message which was simply three smiley faces!
Stylist Briana, 23, and Louis went on a series of dates in May 2015, shortly after he split up from his long-term girlfriend Eleanor Calder.
He confirmed that he was going to be a dad during a chat with Good Morning America last August.
Louis is now on a hiatus from One Direction and has reportedly relocated to Los Angeles, where Briana is from, so that he can play a big part in his young son's life.
Meanwhile Twitter went into total meltdown before the news was confirmed.
And now it's official! Congratulations, you guys.