Mabel Ray arrived on April 1, 2012 in Los Angeles, his rep confirms to People. Mabel weighed in at 9 lbs., 1oz and is "healthy" and "doing beautifully".
Willis has three other daughters — Rumer, 23, Scout, 20, and Tallulah, 18 — with ex-wife Demi Moore.
The couple have been married for three years.
Photo Source: WireImage