Marking the occasion on Sunday with pink and blue balloons, custom-made French pastries, confetti and lots of toys, Carey, 42, and Cannon, 31, had a ball toasting Moroccan and Monroe alongside several close friends at the Plaza Athenee.
In addition to the twins' special day, mom Carey and dad Cannon did a little celebrating while in Paris this week. On Friday, the duo marked their fourth wedding anniversary with a vow renewal ceremony in the City of Light.
Saying "I do" all over again has become an annual event for the couple.
"I have to do it every single year," Cannon has explained to Us Weekly of the renewals. "If you were married to Mariah Carey, you'd want to marry her every year too! I just have to keep doing it to make sure it's real."