Little Riley -- who was born in Seattle, Washington -- weighed in at 6 lbs., 8 oz., and is 18¾ inches long.
The proud papa told PEOPLE that Riley “has a full head of hair — probably more than I’ll have in the next few years.”
“What’s amazing to me is when Molly is holding Riley, her eyes do not come off her,” Jason told the mag. “I’m already seeing how much Molly loves the baby.”
Jason, 36, and 28-year-old Molly’s journey to love has been unusual -- to say the least.
Mesnick -- a divorced dad -- competed on the fourth season of The Bachelorette, which premiered in May 2008, as one of the suitors of bubbly DeAnna Pappas. He proposed in the final rose ceremony before Pappas stopped him. Mesnick was then chosen to star on the 13th season of The Bachelor, which premiered in January 2009.
On The Bachelor, Mesnick proposed and became engaged to Melissa Rycroft, a 25-year-old former squad member of the Dallas Cowboys Cheerleaders. On the season's finale, Mesnick shocked viewers when he announced he had changed his mind. Rycroft was brought out, he broke up with her, and she returned the engagement ring. Molly Malaney, the runner-up, was then brought out; Mesnick asked for another chance with her; and she accepted. The couple tied the knot the next year – in 2010.
This is the first child together for Jason and Molly. Jason has another child -- 8-year-old Tyler -- from his previous marriage to Hilary Buckholz, which ended in divorce in 2007.