The 25-year-old rapper welcomed Kulture Kiari Cephus during a post on Instagram Wednesday, which her representative confirmed. The girl was born Tuesday.
"Kulture Kiari Cephus 07/10/18 @offset," the caption read on a photo showing the rapper nude and very pregnant.
It's the 25-year-old's first child with husband and fellow rapper Offset, whose legal name is Kiari Kendrell Cephus.
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The announcement comes two weeks after Cardi B, whose real name is Belcalis Almanzar, confirmed she and rapper Offset, of the hip-hop group Migos, had secretly married in September 2017.
This is the fourth child for 26-year-old Offset, whose real name is Kiari Cephus.
CNN contributed to this story.