Peter grew up in Ozone Park, Queens, New York, the son of Italian immigrants Bruna, a homemaker, and Peter Facinelli, Sr., a waiter. He studied acting at the Atlantic Theater Company Acting School in New York City; his teachers there included William H. Macy, Felicity Huffman, Giancarlo Esposito, and Camryn Manheim.

He met his future wife, Jennie Garth, on the set of An Unfinished Affair, a 1996 made-for-TV movie. They married on January 20, 2001. He and Garth have three daughters together: Luca Bella (June 22, 1997), Lola Ray (December 6, 2002) and Fiona Eve (September 30, 2006).

He starred in Hollow Man 2 with Christian Slater. It was released direct-to-video in May 2006. He was also in films such as Riding in Cars with Boys, The Scorpion King, and Can’t Hardly Wait. In 2004 and 2005, he was a recurring guest on the hit HBO show Six Feet Under. He also appears on the FX original series Damages. Facinelli played Carlisle Cullen in the movie Twilight.