Mabel Ray Willis, who weighed 9 lbs. and 1 oz, was born Sunday in Los Angeles.
Willis' publicist said the couple is "overjoyed," and both mom and baby are "healthy and doing beautifully."
This is the couple's first child together. Willis, 57, and Heming, 33, were married in 2009.
Willis has three daughters, 23-year-old Rumer, 20-year-old Scout and 18-year-old Tallulah, from his previous marriage to actress Demi Moore.
The Associated Press contributed to this report.