The 47-year-old actress and her French husband, also 47, welcomed a son in Los Angeles Saturday, Berry's publicist told ABC News.
Berry broke the news in April that she was unexpectedly expecting.
"This has been the biggest surprise of my life, to tell you the truth," she told CNN. "Thought I was kind of past the point where this could be a reality for me. So it's been a big surprise and the most wonderful."
Martinez revealed the news that they were expecting a boy in June at the Champs-Elysees Film Festival, where he told People magazine, "My son will be an American. But I remain French."
The couple confirmed their engagement last March and recently tied the knot in France's Burgundy region in July during an intimate ceremony attended by 60 guests.
Berry, who had been married twice before, once vowed never to do it again.
"The traditional form of marriage is not for me," she said.
This is the first child for the couple. Berry has a 5-year-old daughter, Nahla, from her previous relationship with model Gabriel Aubry.