An e-mail from a representative for the former Spice Girl says the couple "welcomed their new baby girl in Los Angeles" on Thursday night.
The e-mail says "this is the first child for Brown and Belafonte and both Mom and Baby are happy, healthy and doing well."
There were no other details.
The 36-year-old formerly known as "Scary Spice" has two older daughters.
Brown and Belafonte were married in 2007.
Belafonte is a movie producer whose credits include "Thank You for Smoking." He has an older daughter.