Haim was introduced to acting when his mother enrolled him in acting classes to help him deal with a tremendous case of shyness. He didn't take to the idea at first because he was simply more interested in things like hockey, playing music on his keyboard and collecting comics. He was, after all, just a kid. But one day his sister, Carol Haim urged him to join her when she was going to audition for a film role. He started to pay attention and went on to appear in several television commercials before getting his first break in a feature film. When he was just 11 years old his parents divorced which may explain some of his later teen years.

Haim began his career when he was just 10-years-old appearing in television commercials and showed a lot of promise in his early work in such films like 1985's Murphy's Romance, and his portrayal of Liza Minelli's dying son in the 1985 made-for-television film A Time to Live.

He became a teen heartthrob with his roles in the 1986 movie Lucas, and The Lost Boys, in which he battled vampires. During the 1990s, his name was often attached to what became a string of your actresses. Alyssa Milano, Nicole Eggert, Holly Fields, Victoria Beckham, and Cindy Guyer were all rumoured to be involved with Haim and he became engaged to three of them: Eggert, Fields, and Guyer. But nothing seemed to last and there were constant rumours about problems with drugs. In a 2007 interview with CNN's Larry King, Haim called himself "a chronic relapser for the rest of my life."

Haim recently appeared in the reality series The Two Coreys with his friend Corey Feldman, but the show was cancelled in 2008 after two seasons. Feldman claimed that Haim's drug abuse strained both their working and personal relationships.

More recently Corey Haim was cast in a few movies, including the 2010 feature American Sunset, but no release date has been set.