Feldman, the second of five children, was born in Chatsworth, California, the son of Sheila (née Goldstein), a cocktail waitress who was once a Playboy Bunny, and Bob Feldman, a rock producer and musician. Feldman is Jewish and has two brothers, Eden and Devin, as well as two sisters, Mindy and Brittnie. Mindy Feldman started her career at age six, as the youngest member of the new Mickey Mouse Club in the '70s.

Corey started his career at the age of three, appearing in a McDonald's commercial. He was also in the TV show Cheers playing a Little Leaguer coached by Coach. He debuted in the films Time After Time & The Fox and the Hound, and starred in such movies as Gremlins (1984), The Goonies (1985) and Stand By Me (1986), alongside River Phoenix and Wil Wheaton. In 1987, Feldman appeared with Corey Haimin The Lost Boys (1987).

Feldman was once a friend of Michael Jacksonuntil a visit to Manhattan, where Feldman claimed that Jackson abandoned him while he and his kids left the city. During the 2005 Jackson molestation trial, Feldman alleged in a 20/20 interview that Jackson had shown him nude photos.

In 1989 until 1990 Corey had dated Drew Barrymorefor a short time but quickly separated. He later married Vanessa Marcil They divorced in 1993. He later married Susie Sprague on October 30, 2002, on the final episode of The Surreal Life. The ceremony was officiated by M.C. Hammer, an ordained minister. Hammer and Mötley Crüe bandmember Vince Neil, both fellow Surreal Life castmembers, performed at the reception. They have one son, Zen Scott Feldman, born on August 7, 2004. Feldman is a vegetarian and is an animal rights and environmental activist. He is a spokesperson for PETA, Farm Sanctuary, The Humane Society, MoveOn, and Greenpeace. He was awarded with the Paws of Fame award by the Wildlife Way Station for his dedication to animal rights