[5] As a distance runner, Yee was the 2018 British 10,000m champion, and led Great Britain to the team silver medal in the European 10,000m Cup as both races were combined as part of the Night of 10,000m PBs festival event at Parliament Hill.

[14] At the ITU Triathlon World Cup race in Cagliari in Sardinia, Italy on 4 June 2017, Yee tangled with another competitor on the bike and crashed into a concrete bollard, suffering broken ribs and vertebrae and a pneumothorax (collapsed lung).

[22] In the build-up to the race, Yee confirmed his view that he was a triathlete first and foremost, despite being a nationally ranked runner, and stated his intentions to qualify for the 2020 Tokyo Olympics.

[26] Team GB recorded a Silver two months later in the same discipline in Tokyo,[27] with Yee being beaten at the line on the final leg by Dorian Coninx representing France.

Learmonth encountered problems on the swim, resulting in Team GB entering T1 in 15th place and unable to make up the deficit on subsequent legs.

[41] He took victory in the final race of the series, held in Malibu, California, crossing the line just fractions of a second ahead of Belgium's Marten Van Riel.

[42] He also took the win at the Super League Triathlon, Jersey race, earlier in the season, finishing ahead of teammate Jonathan Brownlee in the process.

However, following a rule change[46] at the next event, held at Queen Elizabeth Olympic Park London, Yee finished in 2nd, being narrowly beaten by Germany's Justus Nieschlag.

[47] At the final event of the series, held at Marina Bay, Singapore, Yee finished in second place behind New Zealand's Hayden Wilde.

[48] The win came with some controversy, as it was felt that the race should have had a much closer finish, as Yee and Wilde had been running neck-and-neck in the final stages of the sprint, until Wilde was made to serve a 10-second penalty immediately before the finish for unbuckling his helmet strap before his bike had been properly racked in transition, for which "video evidence for the supposed misdemeanor remain(ed) inconclusive".

[49] Yee won a second Commonwealth Games gold in the mixed relay with Sophie Coldwell, Sam Dickinson, and Georgia Taylor-Brown.

[52] Yee also took home the bronze medal in the team relay, alongside Georgia Taylor-Brown, Sam Dickinson and Beth Potter.