Catherine started her career as a comedian in 1974 in Toronto as a cast member of a theater troupe named 'The Second City'. Spending few years of her life as a comedian in a smaller theater group finally, in 1976, O'Hara got the chance in a television film named The Rimshot followed by roles in several other television shows like Coming Up Rosie, Witch's Night Out, and Intergalactic Thanksgiving. But it was only after her performance in a show both as a writer and actress for SCTV and SCTV Network 90, she gained admiration and fame and earned her first Emmy Award for outstanding writing.
She made her feature debut in 1980 film Double Negative and later appeared with more prominent roles in movies like Home Alone, and Monster house. Catherine O'Hara is a Canadian-American by nationality and belongs to white ethnicity. She married Bo Welch, a production designer in 1992 at the age of 38 and has two sons Mattew and Luke with her husband. Catherine earns her salary as a writer and comedian which adds to her net worth of U.S $ 8 million.