The "I Like It" rapper made the announcement tonight on Instagram, in a lengthy post explaining that she "underestimated this whole mommy thing."
Cardi signed on to tour with Mars before finding out she was pregnant with her first child, Kulture, with husband Offset.
The star only had a six-week break between giving birth and going on tour, and had originally planned to bring Baby Bartier with her, but was told by doctors it wasn't a smart move.
Cardi said she's "just not ready physically" to put her body through the rigors of a tour and, emotionally, isn't ready to leave Kulture for that long.
She thanked her fellow "Finesse" singer, Bruno Mars, in the caption, saying, "I hope you guys understand. This have been such a hard decision. I want to thank @brunomars for understanding."
Mars posted a sweet "message for Cardi" on his Instagram, saying he knows the fans will understand and she's "absolutely doing the right thing."
The Grammy winner also vowed to play "Bodak Yellow" at every stop on The 24K Magic Tour.