The new addition to the Arquette family was born at 12.35pm in LA on Monday, weighing 8lbs 7oz. He is a baby brother for Coco, David's nine-year-old daughter with ex-wife Courteney Cox.
"Mum, dad and baby are doing well," the actor's rep told People. "They appreciate all of your well wishes and thank you for respecting their privacy at this time."
David, 42, and Christina, 33, started dating in 2011, but split in mid-2012. "Sadly I'm single again," he tweeted at the time. "A long distance proved to be too difficult."
The couple rekindled their romance, and in November announced they were expecting a baby together.
It was Courteney who revealed the gender of the new arrival. "They're going to have a baby boy," she divulged during an interview with Ellen DeGeneres in January. "I hope I'm allowed to say that."
Courteney and David were married in June 1999 — in October 2012, they confirmed they were having a trial separation. David finally filed for divorce in 2012.
Friends star Courteney has since found love with Snow Patrol's Johnny McDaid.