Simbine was a World Championships finalist in the men's 100 metres in 2017 (fifth) and 2019 (fourth), and was 100 metres champion at the 2018 African Championships and 2018 Commonwealth Games. In the 4 × 100 metres relay he helped South Africa become champions at the African Championships in 2016 and 2018, and place second at the 2018 Commonwealth Games with a South African record time of 38.24 seconds. He anchored South Africa to gold at the 2021 World Relays.