In the sweet snapshot, little Oliver -- showcasing a bit of hair -- looks wide-eyed, swaddled tightly in a blanket.
No doubt the new dad, the season eight American Idol winner, 28, has been enjoying this special time with his family.
"I am really excited," he gushed earlier this year. "I've always wanted to be a dad…[Katy] already started buying him clothes like mine. He's already got some [fedoras]."
On July 30, his rep confirmed the baby's arrival. "Little Oliver Neil Allen is here!" the rep told Us Weekly. "He's 7 pounds, 7 ounces, 20 3/4 inches long. Mom and baby are doing great."
In a tweet on July 31, Allen said that fatherhood has been "amazing" so far.
Together since high school, the singer and O'Connell married in Sept. 2008.