The singer gave birth to a girl and a boy Saturday at an undisclosed hospital in Los Angeles.
According to reports, the 41-year old Carey was calm, but her husband was so nervous, he went to the wrong department at the hospital.
The couple has not named the twins yet. As for having more kids, Carey has recently declared she's done.
The two are expected to renew their wedding vows on Sunday.
The Associated Press contributed to this report.