Marissa Mayer, chief executive of technology company Yahoo, gave birth to twin girls early on Thursday morning.
In a post on her tumblr page, she wrote: "Zack and I are excited to announce that our identical twin girls have arrived!" adding "Our whole family is doing great!".
She is expected to take "limited" time off for maternity leave.
Yahoo announced on Wednesday a plan to spin off its core internet business into a separate company.
Ms Mayer and her husband Zachary Bogue have a three-year-old son, Macallister.
After his birth she took just two weeks off, sparking criticism that she was setting a bad precedent for working mothers at Yahoo.
The company officially offers 16 weeks of maternity leave.