The 38-year-old Olympian confirmed “Nico Michael Phelps” was born January 16 last week, adding that he and his wife Nicole are “blessed” to now be a “family of six.”
The pair shared the news in a joint Instagram post on Monday, sharing a beautiful photo of them admiring their new baby.
A shirtless Phelps held his baby boy while resting his head on his wife as she smiled at their bundle of joy.
Phelps wore his hair up in a bun with a chain around his neck while Johnson opted for a blue button-down shirt.
“@mrs.nicolephelps and I wanna welcome Nico Michael Phelps to the world,” the 23-time Olympic gold medalist wrote.
“Born on 1/16.
“We’re so blessed to be given a 4th child. We’re now a family of 6!”
Fans were quick to share their excitement over the news.
“A whole relay team! Congrats!” one fan wrote.
“Bro gonna watch his sons win gold in all the relays,” another added.
“Congratulations!!!!” NFL star, JJ Watt wrote.
Phelps’ sister, Hilary Phelps also shared her well-wishes, writing: “Alexander and I cannot wait to meet him. sending you all so much love and blessings on the newest arrival!”
The duo are already parents to sons Maverick, 4, Beckett, 5, and Boomer, 7.
Johnson revealed she was expecting baby number four in an anniversary post on October 30, 2023.
“A memory from Oct 29 over the last 7 years with you @m_phelps00 (I couldn’t find 2019s pic) Happy Anniversary to my best friend, hubby and partner thru life. I couldn’t have asked for anyone better!
“For those that are wondering… yes! we’re expecting our 4th Phelps in 2024,” she wrote in the caption.
Phelps and Johnson dated on and off for a few years before the athlete popped the question in 2015.
They tied the knot just one year later in 2016, holding three separate ceremonies.
The couple welcomed their first boy, Boomer, that same year.
Phelps opened up about growing his family in an interview with Today at the end of last year.
“I feel like I’m the best me, the best version of myself, when I’m present and in the moment … and now having four little homies running around, I want to be as present and as active as I can in their life,” he told the outlet.