[9] His younger brother Henry is also a modern pentathlete and competed for Great Britain at the 2014 Summer Youth Olympics.

[12] He qualified for the modern pentathlon at the 2016 Summer Olympics by finishing seventh at the 2015 European Championships held in Bath.

[17] At the 2018 World Modern Pentathlon Championships held in Mexico City, he won a team silver together with and Jamie Cooke and Myles Pillage.

[18] In 2019, Choong won a silver in the individual event at the Modern Pentathlon World Cup held in Sofia, Bulgaria.

[20] The following month at the 2019 World Modern Pentathlon Championships held in Hungary, Choong again won silver in the individual event.

[24][25] Choong was appointed Member of the Order of the British Empire (MBE) in the 2022 New Year Honours for services to modern pentathlon.