The baby boy, whom the new parents named Jonathan Rosebanks Shulman, was born in L.A. on March 24, the rep also confirmed.
This is the first child for Hathaway, 33, and Shulman, 35. The couple married in 2012 after several years of dating.
Earlier this year, amid pregnancy rumors, the actress shared a photo of herself in a bikini, baring her pregnant stomach.
"Posting a bikini pic is a little out of character for me, but just now while I was at the beach I noticed I was being photographed. I figure if this kind of photo is going to be out in the world it should at least be an image that makes me happy (and be one that was taken with my consent. And with a filter," she wrote. "Wishing you love, light and blessings for the year ahead!"