January Jones gave birth to her first child on Tuesday.
The actress, known for playing Mad Men housewife Betty Draper, welcomed a boy who she has named Xander Dane Jones.
January's representative told People that both mother and son are "doing great".
The 33-year-old actress chose not to learn the baby's sex before the birth, revealing in an interview in June: "It's going to be a surprise for me."
January - who this year starred in the film X-Men: First Class - announced the pregnancy in April but has not revealed the identity of the baby's father.
A source told People at the time: "She's really looking forward to this new chapter in her life as a single mom."