Braydon Hart Wilkerson is the second child for Hart and her husband Mark Wilkerson, who is a member of the band Course of Nature, People.com said.
The couple, who married in 2003, also has another son, 2-year-old Mason.
Braydon was born at about 3 p.m. Wednesday.
"This has been a long but exciting pregnancy and we along with Mason are excited to add to the Wilkerson clan," Hart told People.com.
"Melissa and I are the proudest parents ever and this is the best thing that has happened to us this year," Wilkerson added.