How cute is this picture of the baby's hand wrapped around Dec finger!
Declan Donnelly has become a dad, and he couldn't wait to tell everyone the exciting news.
As well as posting the pic on Twitter, they also revealed the baby's name: Isla!
He wrote: "Ali and I are thrilled to announce the arrival of our baby girl, Isla Elizabeth Anne, who was born just after 9 o'clock this morning.
"Mother and daughter both doing well, Dad is head over heels! D x"
Her birth comes just a few weeks before Dec heads to Australia to film the new series of I'm a Celebrity.
With Ant McPartlin taking a break from TV presenting, it'll be Holly Willoughby who Dec is teaming up with this time around.
Holly has three kids of her own, so we're sure she'll be able to give her new presenting partner lots of advice when it comes to looking after a new baby.
But it was Ant who was one of the first to congratulate Dec and Ali on baby Isla's arrival.
Writing on Twitter he said: "Welcome to the world baby Isla Elizabeth Anne. Can't wait for cuddles. I love you already!!".
He signed the message: "Uncle Ant".
Dec's Britain's Got Talent colleagues have also been sending their congratulations.
Amanda Holden posted to say: "Our family so thrilled for you both. And a lovely name xxx".
Meanwhile Twist and Pulse, who took part in the show back in 2010, wrote: "Congratulations Dec💙❤️ All the best to you and you're family🙏🏼"