Sonia Denoncourt was 13 years old when she started refereeing in 1978. She earned a Bachelor’s degree in Physical Education and Sport at Université Sherbrooke and a Master's degree in Sports Administration at the University of Ottawa. 

In 1994, she became one of the first three Canadian women on the FIFA List of Referees. She was honoured as a Canada Soccer Life Member, in fact of one of the first two women honoured as Canada Soccer Life Members (Sonia Denoncourt and Janine Helland) also, honoured by the Canada Soccer Hall of Fame as a referee, in fact, the first female referee honoured by The Soccer Hall of Fame (she was also the first non-player honoured) and was a recipient of the Ray Morgan Memorial Award in 1995. She served on the FIFA List of Referees and Assistant Referees for 11 years (1994-2004), including three FIFA World Cups (1995, 1999, 2003) and two Olympic Games (1996 and 2000) set the record for most matches refereed in the FIFA Women’s World Cup (nine matches from 1995 to 2003). 

She also holds the distinction of being the first female referee to officiate a men’s professional soccer game in Brazil (opening match of the Sao Paulo Soccer Championship on 8 February 1997, Palmeiras v Sao Jose). Additionally, Sonia served as a Referees Administrator at the FIFA World Youth Championship Netherlands 2005 (FIFA U-20 World Cup), served as FIFA’s Head of Women’s Referees (2005 to 2014) and served as CONCACAF Director of Referees (2015).