The baby, whose name the couple has not yet revealed, was born at 6:22 p.m. in Los Angeles, weighing in at 7 lbs., 4 oz.
McConaughey announced on his website in January that Alves, his girlfriend of two years was pregnant.
"Camila and I made a baby together...," he wrote at the time. "We are stoked and wowed."
Alves, a model and handbag designer, plans to take time off to care for her child.
"More important than anything is that I have a peaceful life and a peaceful home," she said.
