The Gavin & Stacey star confirmed that girlfriend Julia Carey is three months pregnant, according to The Sun.
Corden said: "It's true. We're both absolutely over the moon. We really couldn't be any happier."
A friend revealed that Corden was ecstatic when Carey told him the good news.
"He was a bit of a ladies' man in the past but those days are well behind him," the source said. "He's at the right age to settle down, and has met the girl of his dreams.
"He can't wait to be a dad. Having a baby is a proud moment for James."
Former TV producer Carey - who now campaigns for Save The Children - was introduced to Corden by his ex-flatmate at a party a year ago.