People.com said Vida Alves McConaughey was born at 12:13 a.m. Sunday, and weighed in at 7 pounds, 7 ounces.
McConaughey and Alves, who have been together since 2006, are also the parents of a 17-month-old son named Levi.
"'Vida' is Portuguese for 'life' and that's what God gave us this morning," the actor said on his blog. "Camila's recovering wonderfully and we are both truly honored to welcome this little lady into our family. Thanks for all of your well wishes and prayers along the way, another blessed day, we give thanks."
McConaughey's films include "A Time to Kill," "Contact," "The Wedding Planner," "Sahara" and "We Are Marshall." Alves is a fashion model and designer.