The actress announced on Instagram that she gave birth to a daughter, Daisy Josephine Sudeikis, and shared a photo of the newborn.
The baby was born on the International Day of the Girl, Wilde added, which was October 11.
"There goes the neighborhood," she wrote. "Daisy Josephine Sudeikis. Born, like a boss, on #internationaldayofthegirl."
Wilde, 32, and Sudeikis, 41, announced their engagement in 2013. They welcomed their son Otis, 2, the next year.