Collette, the star of TV's "The United States of Tara," and her husband, musician Dave Galafassi, also are the parents of a 3-year-old daughter named Sage.
UsMagazine.com said baby Arlo Robert Galafassi was born Friday in Australia.
"Toni Collette, her husband, David Galafassi, and their daughter, Sage Galafassi, are excited and proud to announce the arrival of their baby boy, Arlo Robert Galafassi. He was born on Good Friday, making it the greatest Friday indeed," the actress' representative told UsMagazine.com.
Celebrity Couples of 2014 [PHOTOS]