I'm excited and terrified
Fergie, 38, welcomed her son via C-section at an LA hospital on Thursday, with 40 year-old husband Josh Duhamel by her side.
Axl was born weighing 7lbs 10 ounces, according to a representative for the singer.
It is thought the couple named their first child after Guns N’ Roses rocker Axl Rose.
Fergie is reportedly a fan of the band and performed Sweet Child O' Mine with guitarist Slash during the Black Eyed Peas' Super Bowl halftime show in 2011.
The US website that first reported the birth claimed father-to-be Josh was calm about the impending arrival and was seen chatting to hospital staff.
Appearing on The Tonight Show two nights before his wife gave birth, Josh admitted to having some last-minute pre-baby jitters.
‘You know, I gotta tell you, I'm a little bit nervous,’ he said. ‘I thought that I was going to be good. I thought that I was ready for this, and I'm a little bit terrified. I'm excited and terrified, because I am responsible for this little thing. Forever.’
Fergie remains in hospital with her newborn where she is recovering from the surgery.
Back in July, the popstar was thrown a ‘gayby’ shower by her friends Sean Patterson, DSquared fashion designers Dean and Dan Caten and celeb hairstylist Andy Lecompte.
The bash was attended by a host of the singer’s showbiz friends including Kelly Osbourne and Perez Hilton and guests were treated to drag burlesque performers.