The proud daddy took to Twitter last night to reveal the family's exciting news to fans and followers.
The 41-year-old Take That star and X-Factor judge wrote: "My wife and I are expecting our 4th child #Anotherowngoal."
He then went on to joke that he had his eye on Peter Andre's 'Celebrity Dad of the Year' crown, tweeting:"Celebrity Dad of the Year #moveasideandre!"
Gary and Dawn married in 2000, and are already proud parents to Daniel, 11, Emily, nine, and Daisy, three.
The chuffed dad-to-be thanked his 1.3 million Twitter followers for their congratulations, saying: "What a lovely bunch you are. Thank you for all your kind messages.We are a very excited family."
Aw, what lovely news, and another celeb baby on the way!
The question is, will Barlow Jnr join his or her dad for the X-Factor auditions later this year, like baby Hollie Rose did for BGT?
Suggested For You
SUBSCRIBE AND FOLLOW
Get top stories and blog posts emailed to me each day. Newsletters may offer personalized content or advertisements.Learn more