The wife of Manchester United and England captain gave birth to their third son on Sunday, naming him Kit Joseph, according to BBC Sport.
Wayne wrote: "Our gorgeous little boy arrived today. Kit Joseph Rooney. 8Ib 1oz. We are over the moon."
The childhood sweethearts, who married in Italy in 2008, already have two sons - Kai, six, and two-year-old Klay.
It's thought that Coleen, 29, was admitted to the Liverpool Women's Hospital on Saturday ahead of the birth.
Wayne, 30, captained Manchester United at Old Trafford in a 1-0 loss to Southampton.
Like the Kardashians - the Rooneys have given their children names beginning with a K.
The couple simultaneously announced that Coleen was expecting in July with the same tweets.
Last week Coleen wrote that she was still waiting to go into labour.
On Monday she tweeted: "No baby yet!! .... Hurry up!! ..... Too comfy."
The footballer also posted a photo of the family when Klay was born.
In an interview before the birth, Coleen told OK! Magazine they would "definitely not" find out the sex of their baby.
But she told the magazine that she would "love a girl because it would complete the family".
"Hopefully the anticipation of the sex will make the labour go a bit quicker."
