McCormack made his Canadian television debut in the 1986 movie "The Boys from Syracuse"." McCormack moved to Los Angeles, California, and made his US television debut in a 1991 episode of the CBS crime series "Top Cops". He appeared in the 1992 theatrical film "The Lost World", based on Conan Doyle's novel of the same name and starred in "The Lost World" sequel, "Return to the Lost World", also released in 1992. By 1993, he landed a recurring role as a detective in the crime drama "Street Justice". Also in 1993, McCormack appeared in the television movie "Double, Double, Toil and Trouble", playing Mary-Kate and Ashley Olsen's father.