[4] A month later, he formed part of the Great Britain squad that won the gold medal at the 2015 World Aquatics Championships in the men's 4 x 200 metre freestyle relay as the 4th leg swimmer in the heat.

[5] In 2016, he was a member of the Great Britain team that won silver in the final of the same event at the Olympic Games as well as the men's 4 x 100 metre medley relay.

Duncan Scott grew up in Alloa,[6][7] moving to Strathallan School on a sport scholarship at the beginning of secondary.

[8] Scott came to public attention when he won eight gold medals at the 2013 Scottish Age Group Championships in Edinburgh.

[10] He then competed at the 2014 Youth Olympics in Nanjing taking gold in the 4 × 100 m freestyle (with Luke Greenbank, Miles Munro, and Martyn Walton).

[11] In the 2016 Rio Olympics, he won a silver in the 4 × 200 m freestyle relay with Stephen Milne, James Guy, and Dan Wallace.

He won gold in the 4 × 200 m freestyle with James Guy, Stephen Milne and Nick Grainger in a time of seven minutes 1.70 seconds.

[20] He added a third gold in the final day of the championships, winning the men's 4 × 100 metre medley relay as part of the British team with Adam Peaty, James Guy and Nicholas Pyle.

[23] After the medal ceremony, Scott refused to shake hands and take pictures with the gold medallist Sun Yang, who had previously been banned for a trimetazidine drug offence in 2014 for three months and was involved in an ongoing doping case controversy.

[1][24] This transpired following Australian Mack Horton's refusal to share a podium with Sun at the medal ceremony when the Chinese national anthem was played.

[25][26] In the lead-off leg in the men's 4 × 200 m freestyle relay final, Scott broke the British national record with a time of 1:44:91; the team finished fifth in the race.

[41] He followed it up with a gold as part of the 4×200m freestyle relay team with Tom Dean, James Guy, and Matt Richards, winning it in a European record of 6 minutes 58.58 seconds.

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

[53][54][55][56] In mid-July, approximately a week before the start of swimming competition at the 2022 Commonwealth Games, he withdrew from the 2022 European Aquatics Championships.

[79] Scott won the 200 metres medley at the 2024 Aquatics GB Swimming Championships sealing his place at the 2024 Summer Olympics.

[80] Scott was in the final of the Men's 4 × 200 metre freestyle relay together with James Guy, Tom Dean, and Matt Richards, the same four quartet who won in the same event at the Tokyo Olympics.

[83] Scott was appointed Officer of the Order of the British Empire (OBE) in the 2025 New Year Honours for services to swimming.