He was the 2013 European Junior Champion and his personal best of 19.95 seconds ranks him as the second-fastest in Britain of all-time in the individual event.

Part of the Great Britain 4 x 100-metre relay team that won the World title in 2017, he won his first major individual honour, a silver medal, in the individual 200 metres at the 2018 European Athletics Championships before claiming another relay title running for Great Britain, the eventual gold medalists, in the heats of the 4 x 100 metres.

[5] Mitchell-Blake was recruited by Louisiana State University and began to compete for them collegiately with the LSU Tigers team.

[11] He marked a breakthrough at the SEC Outdoor Championships,[13] coming within one hundredth of the British record for the 200 m with his winning time of 19.95 seconds.

[15] He ran the same leg at the 2019 World Athletics Championships, with the team finishing in silver medal position with a new European record of 37.36 seconds.