The movie star and the real-estate agent married last January.
Born Saturday in Vaughn's hometown of Chicago, the couple's daughter weighed in at 7 pounds and measured 20 inches long.
"Both of them couldn't be happier to welcome their sweet little girl into their family!" an unidentified friend told People.com.
Vaughn's film credits include "Couples Retreat," "Old School" and "Swingers."