Haim was born in Toronto, Ontario, Canada, to Bernie Haim, a Francophone Jewish-Canadian sales representative, and Judy, an Israeli-born computer operator. Haim was enlisted in acting lessons by his mother in an attempt to help him overcome his shyness.
Haim, not particularly fascinated by acting, practiced other hobbies such as ice hockey, playing music on his keyboard and collecting comic books.
It was actually his older sister, Carol, who got him initially interested in the notion of acting. She brought him along when auditioning for a film role. At a young age, Haim would appear in several television commercials. When Corey was 11, his parents divorced after 18 years of marriage.
Haim appeared to have finally gotten rid of his drug habit by 2004, after resettling in Toronto. The Irish band, The Thrills, released a single, "Whatever happened to Corey Haim?", in September 2004. In response to an investigation by The Sun newspaper during the single's release into what exactly had happened to Haim, he responded: "I'm clean, sober, humble and happy". Haim is optimistic of returning to the film industry. In 2006 he was ranked #8 on VH1's Greatest Teen Stars.