At the international level, she made her debut for the Canada Maple Leafs senior women's developmental national team as captain on a two-match tour of England. She was called up as an injury replacement for flanker Barbara Mervin in the Canada women's national silver-medal side in the last three weeks of the 2014 Women's Rugby World Cup, which lost 21–9 to England in the final. Nelles played for the Canada women's national rugby union team at the 2015 Women's Rugby Super Series in Alberta. Nelles was named as one of 25 players to Canada's 2017 Can Am rugby team for the series held in San Diego after doing a one-week training camp in Vancouver Island. She went on to play three matches for Canada at the 2017 Women's Rugby World Cup, scoring a single second-half semi-final try against Wales to finish in fifth position. Overall, Nelles has played for the national Canada team 19 times. In November 2020, she was named to the New Zealand Barbarians team that lost 19–17 to the New Zealand national side at Trafalgar Park, Nelson.