The younger sister of double European champion Becky Downie, Downie first came to prominence as an outstanding junior gymnast at the 2014 Summer Youth Olympics, winning four medals. At the age of 15, she became the first British woman to win an individual all-around medal at the European Artistic Gymnastics Championships, with a bronze in 2015. Later that year, she was part of the team that won Britain's first global team medal, a bronze, at the 2015 World Artistic Gymnastics Championships. At the 2017 European Championships, she made history again by becoming the first British gymnast to win the all-around at a major international competition.