William Theodore Kotcheff was born in Toronto, Ontario, Canada, to Bulgarian parents from Plovdiv. He graduated with a degree in English Literature from the University of Toronto. He began his professional career directing TV drama at age 24 at the Canadian Broadcasting Corporation, at the time becoming the youngest director in the CBC. After two years there he went to live and work in England, directing in television and the theatre.

He twice won the British Emmy for Best Director, the second time for an extraordinary docudrama about a female derelict entitled, "Edna, the Inebriate Woman" episode of Play for Today (1970). The film also won the Best Actress and Best Script Award. Kotcheff's television work in Great Britain was part of the new wave of working-class actors and drama that changed British theatre and television in the late 1950s. His stage successes include the long-running Lionel Bart musical, "Maggie May." His film career started in England: Tiara Tahiti (1962), a social comedy starring James Mason and John Mills; Life at the Top (1965), starring Laurence Harvey and Jean Simmons; Two Gentlemen Sharing (1969), starring Robin Phillips, a film set in the West Indian community of London and dealing with relationships between blacks and whites which was the official British entry at the Venice Film Festival. His next film, Wake in Fright (1971), was made in Australia. It was the Australian entry in the Cannes Film Festival and many Australians still think it is the finest Australian film ever made and the beginning of the renaissance of the Australian cinema. Kotcheff returned to Canada in 1972 to make a film of a novel written by his best friend, Mordecai Richler, The Apprenticeship of Duddy Kravitz (1974). This film, thought to be one of the best Canadian films ever made, won the Golden Bear First Prize at the Berlin Film Festival and numerous other awards including an Academy Award nomination for best script. Kotcheff also directed Fun with Dick and Jane (1977), starring Jane Fonda and George Segal; Who Is Killing the Great Chefs of Europe? (1978), starring Jacqueline Bisset and George Segal; North Dallas Forty (1979)--which he also wrote--starring 'Nick Nolte' (a film considered by many in the sport to be one of the best ever made about professional football); First Blood (1982), starring Sylvester Stallone--one of the biggest box-office winners of all time--Uncommon Valor (1983), starring Gene Hackman; and Weekend at Bernie's (1989). In the mid-'80s Kotcheff made a film of another Mordecai Richler novel, Joshua Then and Now (1985). This film, starring James Woods and Alan Arkin, was the official Canadian entry in the Cannes Film Festival, and together with "The Apprenticeship of Duddy Kravitz", is one of the most widely known and acclaimed Canadian films in the United States. Kotcheff is married to Laifun Chung and has two children, Thomas age 7 and Alexandra age 9. Laifun Chung is President of their film company, Panoptica Productions, Inc. He has homes in Toronto and Los Angeles.