The 38-year-old Black Eyed Peas singer underwent a C-section to give birth to son Axl Jack Duhamel, who weighed in at 7 pounds, 10 ounces.
Fergie initially announced in February that she was expecting on Twitter. "Josh & Me & BABY makes three!!!," she tweeted with a link to a picture of her at childhood with a picture of a very young Duhamel cropped in next to her.
Fergie and Duhamel, 40, married in 2009 after dating for more than four years.