The former Saved By The Bell star and Extra host posted a snap of his three-month-old son while catching up on some boxing!
Dominic looked ever so cute, as he lay on the bed in just his nappy while holding his hands together.
Meanwhile Mario, who dressed casually in a blue T-shirt and headband, slouched back on his pillow with the remote control in his hand.
Captioning the snap, 40-year-old Mario said: "Back home. Dominic & I catching up on some fights... #Bonding."
Mario, who also hosts the US X Factor, had earlier spent the day celebrating the launch of Britney Spears' new album, Britney Jean, in Las Vegas.
The proud dad welcomed baby Dominic on 9 September with his wife Courtney Mazza. He revealed the birth of his newborn on Twitter, announcing: "It's a boy! Please welcome Dominic Lopez to the world! Couldn't be happier. Courtney and baby are doing just fine."
Mario and Courtney, who are already parents to three-year-old daughter Gia, showed off their gorgeous family at Dominic's belated baby shower in Los Angeles two weeks ago.
Speaking to Us Weekly, Mario gushed: "He's such a good baby, he has my wife's disposition. Very chill and complacent. As opposed to my daughter who's a little more hyper and crazy like me!"
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Copyright: Love & Lust London