Berry gave birth Saturday at Cedars Sinai Medical Center, People magazine reported.
While this was Berry and Martinez's first child together, Berry also has a 5-year-old daughter, Nahla, with ex-boyfriend Gabriel Aubry.
"Olivier hasn't left Halle's side. Nahla visited her baby brother earlier today," a hospital official told People.
Berry, 47, and Martinez, 47, got married in France in July after announcing in April that they were expecting a child, CNN reported.
"This has been the biggest surprise of my life, to tell you the truth," Berry told CNN in April. "I 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."