"Happy day!!!! My little stud was born today. Oliver is here people," the singer Tweets. The baby boy weighs in at 7 lbs., 7 oz. and is 20¾ inches long. "Mom and baby are doing great," the rep tells PEOPLE.
Allen, 28, and his wife revealed back in January that they were expecting. "I am really excited. I've always wanted to be a dad," Allen later said. "My wife already started buying him clothes like me. He's already got some [fedoras]."
It's been a year of joy but also hardship for Allen. Also in January, he and Katy were involved in a serious car accident that shattered Allen's wrist.