The couple have named their son Jack Blues Bieber, and announced his birth in a post on Instagram on Saturday morning.
A photograph on Justin’s account, shared with his 294 million followers, showed the newborn’s foot.
“Welcome Home,” he captioned the picture. Haileyalso shared the post.
US reality star and entrepreneur Kylie Jenner and singer Katy Perry were among the stars congratulating the couple.
Your blessing has arrived,” Perry wrote.
Within four hours of the news being shared, the post had received more than seven million likes.
Singer Justin, 30, who was discovered online at the age of 13, is known for hits including Baby, Love Me and Yummy.
The Canadian superstar was forced to cancel the remaining dates of his Justice world tour last year amid his ongoing recovery from Ramsay Hunt syndrome, a condition that can cause facial paralysis.
Hailey, 27, is the daughter of actor Stephen Baldwin and niece of actors Alec, William and Daniel Baldwin.
The couple got married in a secret ceremony in New York in 2018, followed by a more lavish ceremony the following year.
They announced the pregnancy with video and images from a photoshoot of Hailey debuting her bump in a white lace dress earlier this year, during an apparent vow renewal held in a field.