"Whoa, cutting it close. Just wrapped @TheXFactorUSA & I'm rushing to the hospital. Baby Lopez #2 is coming tonight," he Tweeted while en route to meet his wife Courtney at the hospital, who went into labor early.
You can see Mario race out of the X-Factor and change into scrubs before joining his wife in the operating room. Just 20 minutes later, his son Dominic arrived. "It's a boy!" he cheers while fist-pumping.
The busy dad, who already has a 3-year-old daughter, will be back on set to host Extra today and is promoting tonight's season premiere of X-Factor, too.
"Dominic also didn't want to miss the premiere of @XFactorUSA tomorrow night on Fox! The kid has got some good timing," Mario Tweeted.
All in a day's work!