The Hollywood actress, 30, proudly took to Twitter to announce the news in an amusing post.
“Ladies and gentlemen, Otis Alexander Sudeikis has LEFT the building! (I'm the building),” she tweeted, alongside a black and white photo of mother and baby.
Ladies and gentlemen, Otis Alexander Sudeikis has LEFT the building! (I'm the building) pic.twitter.com/uHfY3adroc— olivia wilde (@oliviawilde) April 23, 2014
In the sweet snapshot, Olivia is pictured cradling her newborn son close and smiling with her eyes closed. The bundle of joy is wrapped up in a blanket and nestled into his mother’s chest, with his face hidden from view.
The image caused a stir on Twitter and was retweeted more than 4,000 times in less than four hours.
This is the first child for Olivia and Jason, who announced that they were expecting a child last October.
The Rush actress confirmed early on that she was having a boy, and hinted at the 2014 Golden Globes that her due date was on 4 May, as she told Ryan Seacrest, "May the fourth be with you!" when probed.
Olivia and Jason, who have been dating since November 2011, got engaged in January 2013.