In an Instagram post, Bieber shared a picture of his newborn son's small foot.
"Welcome home," Bieber wrote in the caption in the early hours of Saturday morning, revealing his name as Jack Blues Bieber.
Katy Perry and Kylie Jenner were among the famous faces who congratulated the couple.
"Your blessing has arrived," Perry wrote as a comment to Bieber's post.
Meanwhile, Jenner wrote: "I can't handle this little foot".
Announcing their pregnancy in May, the couple shared a video and images of Hailey debuting her bump in a white lace dress.
The 27-year-old American model and the pop singer got married in a secret ceremony in New York in 2018.