A representative for the former Newlyweds star confirmed on Monday morning (1 July) that Jessica and fiance Eric Johnson had become parents to son Ace Knute Johnson via a scheduled Caesarean section on Sunday, 30 June.
'Knute' is a tribute to Eric's grandfather, who hails from Sweden.
Jessica's dad Joe has also confirmed the news via Twitter, writing: "Very blessed to celebrate the birth of my new grandson."
The little boy is Jessica and Eric's second child. They are also parents to daughter Maxwell, who was born in May 2012.
32-year-old Jessica and 33-year-old former NFL player Eric confirmed their second pregnancy on Christmas Day, while they were on holiday in Hawaii, by posting a photograph of Maxwell playing in the sand alongside the message 'Big Sis'.
Jessica accidentally revealed her second child's gender during an appearance on US TV earlier this year, when she spoke about how this pregnancy was making her feel more nauseous.
The star has been engaged to Eric since November 2010 but joked earlier this year the couple haven't made it down the aisle yet because she "keeps getting knocked up".