He also competed at the 2020 European Championships where he won three gold and two silver medals in the team events and one individual bronze in 200m freestyle.

[21] He then won gold in the men's 4 × 200 metre freestyle relay together with James Guy, Duncan Scott, and Matt Richards in a time of six minutes 58.58 seconds.

Dean became the first male British swimmer to win two gold Olympic medals at the same games in 113 years, a feat later equalled in the same week by James Guy and Adam Peaty.

[22] Dean was appointed Member of the Order of the British Empire (MBE) in the 2022 New Year Honours for services to swimming.

[28][29][30] Also in 2022, he was part of the team that won the gold medal in the Men's 4 × 100 metre medley relay at the 2022 Commonwealth Games in Birmingham.

In the men's 4 × 200 metre freestyle relay, the same quartet of British swimmers who won in the same event at the Tokyo Olympics – James Guy, Duncan Scott, Matt Richards and Dean – swam in the final.

[39] Dean was partnered with Nadiya Bychkova and they were the first couple eliminated in week two, after losing the dance-off to Toyah Willcox and Neil Jones.