The Supernatural star shared the news via Twitter on Monday.
"Hey yall- gen and I did, indeed, experience a holiday miracle yesterday: Tony Romo didn't senselessly throw the game away," he teased on the social media site.
"Ok. For real ;) My amazingly strong wife home-birthed a happy and healthy baby boy last night :). Please send love," he explained in a second post.
The Padaleckis are already parents to 1-year-old Thomas Colton.
The actor wished his fans a Merry Christmas from his whole family while going through hoops not to reveal his new baby's name on Twitter Wednesday.
We just wanted to wish everybody out there a safe and happy holiday season, from the four Padaleckis. Sincerely: Me, @realGpad, Thomas, and— Jared Padalecki (@jarpad) December 26, 2013
Those damn 140 characters ALWAYS get the best of me! Embarrassingly, it cut off our new sons name! Sheesh. Crazy! Anyways, PLEASE HELP WELCO— Jared Padalecki (@jarpad) December 26, 2013