George confirmed the news via Twitter, writing: "@KerryKatona77 Thank you for bringing my beautiful daughter into this world last night!"
The Atomic Kitten singer, 33, gave birth to her baby girl on Friday night. She is already mum to Molly, 12, and Lilly-Sue, 11, from her marriage to Brian McFadden and Heidi, 7, and Max, 5, from her relationship with Mark Croft.
Kerry's band mates were among those to wish her and George their congratulations, with Natasha Hamilton tweeting: "And a huge congrats to @KerryKatona77 and @mrgsjkay on the arrival of their baby girl. Can't wait to get back to the UK and get some cuddles xxx."
Liz McClarnon obviously beat Natasha to it, as she tweeted: "Well I'm in love, baby Katona/Kay is perfect. I met her finally last night."
Just last week, Kerry posted a picture on Instagram of her huge bump, with the caption: "Can't even see me feet anymore!!" The couple are yet to announce the name of their new addition.
Congratulations to Kerry and George!