Davis has been teaching acting for fifty years. His first teaching assignments were with major British theatre schools; The London Academy of Music and Dramatic Art and The Guildhall School of Music and Drama. In the mid-sixties he returned to Canada to The National Theatre School of Canada serving for one year as Assistant Artistic Director and for four years as Artistic Director. In the early seventies alongside his position as Artistic Director of Festival Lennoxville he was an Associate Professor of Drama at Bishop's University. Later, on returning to Toronto he worked as a freelance teacher for Tarragon Theatre and Canadian Actors' Equity before taking a teaching position at Humber College where he remained for three years until professional commitments conflicted.

In 1985 Davis moved to Vancouver BC to head The Vancouver Playhouse Acting School and from there went on to found and run The William Davis Centre for Actors' Study. The William Davis Centre operated at the famous corner of Hornby and Helmcken Street in Vancouver for fifteen years. When his acting commitments began to take all his time, Davis sold the school which has subsequently become part of VanArts.

Davis still loves to teach and has done workshops across Canada and teaches from time to time at The William Davis Centre at VanArts.

His next book promises to be about acting.