The baby joins Caspar, 7, and Clementine, 5, Schiffer's children with husband Matthew Vaughan, a film producer whom she married in 2002. According to a report in German newspaper Welt am Sonntag, the supermodel, 39, is expected to reveal the baby's name in the coming week.
The baby was delivered in London's Portland Hospital.
"I am much more self-confident today," Schiffer said in an interview with Welt am Sonntag shortly before giving birth, "because of my children and my husband. I know what I am doing, what I want [and] I am in control of myself."
The supermodel also recently posed nude – and pregnant – in German Vogue.