Rankoe began gymnastics when she was eight years old.[1]
Rankoe won a silver medal with the South African team at the 2012 African Championships, and she placed fifth in the balance beam final.[2] At the 2013 Serbia Memorial Cup, she won the all-around silver medal and won a gold medal on the uneven bars.[3] She won the silver medal in the all-around at the 2014 African Junior Championships behind Egypt's Nada Ayman Ibrahim,[4] and she helped South Africa win the team silver medal behind Egypt.[5] She was then selected to represent South Africa at the 2014 Summer Youth Olympics.[6][7] There, she finished 33rd in the all-around during the qualification round and did not advance into any finals.[8]
Rankoe became age-eligible for senior international competitions in 2015. She placed fifth in the all-around at the 2015 South African Championships.[9] She missed the rest of the 2015 season due to a shoulder cyst.[1] She returned to competition at the 2016 South African Championships and won bronze medals on the balance beam and floor exercise.[10] She competed on the uneven bars and the balance beam at the 2017 Koper World Challenge Cup but did not advance into the finals.[11]
Rankoe won the all-around silver medal at the 2019 South African Championships behind Naveen Daries.[12] She then competed at the 2019 Guimaraes World Challenge Cup and finished seventh in the uneven bars final.[13] She was selected to compete at the 2019 World Championships, and she placed 133rd in the all-around during the qualification round.[14]
Rankoe placed fifth in the all-around at the 2021 African Championships and did not win an Olympic berth.[15] She finished fifth in the balance beam final at the 2022 African Championships and won a silver medal with the South African team.[16] She was then selected to represent South Africa at the 2022 Commonwealth Games and helped the team place fourth. She announced her retirement after the Commonwealth Games.[17]