Liam shared an adorbs Instagram snap holding his newborn son and wrote: "My close friends and family know there are very few times when I'm left speechless... wow!
"I'm incredibly happy to welcome our new baby boy into the world, it's a moment that I will never forget for the rest of my life and my favourite memory I have so far.
"I'm completely in awe of his incredible mother and how she has been the whole way through this, she's really made my dreams come true. We haven't named him yet but he's already capturing hearts including mine. I feel very blessed.
Happy Mother's Day everyone!"
Cheryl shared the same photo from her Instagram account and wrote: "On Wednesday 22nd March Liam and I became parents to an incredibly beautiful, healthy baby boy, weighing 7lb 9 and looking like a dream.
"Although he still doesn't have a name he is already stealing hearts. We are all madly in love and overwhelmingly happy with our little arrival. Happy Mother's Day to all the mothers around the world. A day that now has a different meaning to me forever."
The pair started dating in May 2016 and first met when Liam auditioned on The X Factor in 2009 - Cheryl was on the judging panel.
He told The Sun: "Obviously I have the most beautiful girlfriend in the world and she’s absolutely amazing. She’s been my dream girl since I was younger. She’s so ace."
Cute! Congrats guys!