Johnson and his girlfriend Lauren Hashian took to Instagram to share a pic of her baby bump.
"I was raised by and live with amazing and strong women, so the universe felt we needed one more...IT'S A BABY GIRL!!" he wrote.
The former pro wrestler continued, "THANK YOU guys so much for the awesome support and love you've sent @laurenhashianofficial and myself from around the world. We're so grateful for this blessing and thrilled to share the news with y'all. #BringOnMoreEstrogenInOurHome #MeAndPuppyHobbsAreTheOnlyDudes #Proud2xPapaBear #JustOverHereMakingBabiesAndStuff."
Johnson, 43, already has a daughter Simone, 14, from a previous relationship. He was married to Dany Garcia until 2007 and began dating Hashian after they split.
Earlier this summer, Johnson opened up about his girlfriend in an interview with Esquire.
"I've lived with my longtime girlfriend, Lauren Hashian, going on, like, eight, nine years now. She's a singer-songwriter," he said. "We spend a lot of time with my daughter, Simone, who's 13. We do these stories and we talk so much about the business end, the success end, but then Lauren isn't mentioned and my daughter isn't mentioned," he said, making sure she got a nice shout out."
"You gotta get the better half in there," he added. "With all the cool s--- and success that I've been lucky enough to get? That doesn't happen unless the home life is solid."