After graduating from Stanford University in 2017, Courtney began racing full-time and in her first full season in 2017 won four U23 World Cups and the U23 World Cup overall title, and took a silver medal at the U23 world championship. She is also a two-time US cross-country (XC) national champion, having won the title in 2017 and 2018. Courtney participated at the 2018 UCI Mountain Bike World Championships, winning the gold medal in the women's elite cross country race. It was the first such win for an American since 2001.