Kardashian tweeted “He’s here!” on Twitter and an announcement on her website read, “KANYE AND I WELCOME OUR BABY BOY!” The website said mother and son were doing well.
The couple did not provide a name for the boy.
Kardashian has kept fans informed of the progress of her pregnancy on Twitter, saying “Ready whenever you are lol” on Friday and posting an image of her bare belly.
She announced in June that she and West were expecting a baby boy. The couple has a daughter, North West, who was born in 2013.
West and Kardashian started dating in 2012. Their daughter was baptized in Jerusalem in April.
The couple married last year in a lavish ceremony in the 16th-century Belvedere Fort overlooking Florence, Italy.