"I gave birth to our son Noah Shannon Green on September 27th," Fox wrote on her Facebook page. "He is healthy, happy, and perfect."
Green, 39, and Fox, 26, wed in June 2010 after dating on and off since meeting on the set of Hope & Faith in 2004. This is the first child for Fox and the second for Green, who has a 10-year-old son with Vanessa Marcil.
"We are humbled to have the opportunity to call ourselves the parents of this beautiful soul and I am forever grateful to God for allowing me to know this kind of boundless, immaculate love," Fox added. "Thanks to those of you who wish to send your positive energy and well wishes. May God bless you and your families abundantly."