He even calls himself Tío Mario.
Mario shared the cutest pic of Santi taking a nap and he's just so cute! The TV host was all smiles, with his dimple on full display, while visiting the baby. "This is some of your best work @EvaLongoria... #Santiago #BabyBaston #LoveHim #TíoMario," he captioned the snap.
The two friends previously discussed if Mario would be the baby's godfather.
"When are you going to officially ask me to be the godfather to your child?" he asked Eva on his show Extra in May 2018. "Because in all seriousness, who else is going to be a better Catholic and male role model than me?" Eva was quick to fire back and ask him why she wasn't chosen as a godmother for his two kids, Dominic and Gia.
The pair have been friends forever!
Eva and Mario have been friends for over a decade. They've been by each other sides throughout their careers, with the actress appearing on his talk show Extra several times through the years and him supporting her acting projects. He was present at the ceremony for when Eva received her star on the Hollywood Walk of Fame in April 2018.