Great Britain, or in full Great Britain and Northern Ireland, the team of the British Olympic Association (BOA), which represents the United Kingdom, competed at the 2020 Summer Olympics in Tokyo. Originally scheduled to take place from 24 July to 9 August 2020, the Games were postponed to 23 July to 8 August 2021, because of the COVID-19 pandemic.

British athletes have appeared in every Summer Olympic Games of the modern era, alongside those of Australia, France, Greece, and Switzerland, although Great Britain is the only team to have won at least one gold medal at all of them. This streak was maintained in Tokyo when Adam Peaty successfully defended his 100 metre breaststroke title on the third morning of the Games.

The first medals of the Games for Great Britain were won by martial artists with taekwondo-ka Bradly Sinden guaranteeing Team GB at least a silver medal by qualifying for the final of the −68 kg event in taekwondo. Before the final took place, however, judoka Chelsie Giles secured a bronze medal in the 52 kg class via the repechage.

Summary

The 2020 Games saw members of the Great Britain team achieve a number of prominent milestones. In the pool, Adam Peaty became the first British swimmer to successfully defend an Olympic gold medal, winning the 100 metre breaststroke for the second time. The British swimming team also had its most successful Olympics in history winning eight medals (with four golds) eclipsing the previous Olympic swimming best of seven medals (which also included four golds) which had stood since the London 1908 Games (113 years). This included a 1–2 finish in the final of the Men's 200m freestyle for Duncan Scott (who took silver) and Tom Dean (who took gold) which was the first time British swimmers had achieved this in any Olympic swimming event since 1908. Scott also became Britain's most successful athlete in any sport at a single games in terms of number of medals won with four medals in total made up of one gold and three silver medals. However, Adam Peaty, James Guy and Tom Dean were more successful in terms of gold medals winning two golds to Scott's single gold. By winning gold alongside James Guy and Adam Peaty in the mixed 4 × 100 metres medley relay Freya Anderson, Kathleen Dawson and Anna Hopkin became the first British female swimmers since Rebecca Adlington took double individual gold in the 400 metre freestyle and 800m freestyle events at the Beijing 2008 games to win an Olympic gold medal. However, no British female swimmer won a medal in any of the individual women's events making the medals from mixed medley the only ones won by British female swimmers at the Games.

On 4 August Sky Brown became the youngest British Olympian ever to win a medal when she won bronze in the Women's Park Skateboarding at the age of 13 years and 28 days.

Gymnast Max Whitlock also clinched his second consecutive Olympic title on the pommel horse becoming one of the most successful gymnasts ever in the history of that specific apparatus – having also won three World Championship titles in the discipline – and the fourth man in Olympic history to successfully defend their pommel horse title. In doing do he cemented his position as Great Britain's most successful Olympic gymnast with six medals overall including three golds. Bryony Page in the Women's Trampoline competition claimed her second consecutive Olympic medal in the event with a bronze medal having won a silver in Rio. A team containing Jennifer Gadirova, Jessica Gadirova, Alice Kinsella and Amelie Morgan also won a Bronze in the Women's Team Artistic All-Round event. giving the gymnastics squad three medals at Tokyo 2020 overall down from the seven achieved by gymnastics in Rio in 2016.

Keely Hodgkinson and Laura Muir secured silver medals in the Women's 800 metres and 1500 metres respectively. These were the first medals in either of these events for a British athlete since Kelly Holmes won double gold at the Athens 2004 Games. Josh Kerr by winning bronze in the Men's 1500m also became the first British athlete to win an Olympic medal in that event since Seoul 1988 where Peter Elliott won a silver medal. Holly Bradshaw also won her first medal in either Olympic or outdoor World Championship competition with bronze in the women's pole vault. The women's 4 × 100 relay squad also won a bronze.

Despite failing to medal in the men's match sprint Jason Kenny took sole ownership of the record as Great Britain's most successful Olympian, most decorated Olympian and the most successful and most decorated Olympic cyclist of any nation, with silver in the men's team sprint and gold in the men's keirin. This was the fourth consecutive keirin title for Great Britain, and took Kenny's career tally to seven gold and two silver medals and was the fourth consecutive Olympics in which he had won one or more golds. His wife Laura Kenny lost her omnium title after a major crash in the opening scratch race, and only managed a silver medal in the women's team pursuit. However, in the inaugural Olympic women's Madison she and partner Katie Archibald won the event, gaining a lap and winning all but two of the intermediate sprints. This took her career tally to five golds and one silver making her the most decorated British female Olympian, and the most successful and most decorated female Olympic cyclist of any nation. Together the Kennys also became the most successful married Olympians in history where both partners have won a gold medal. Britain's other track cycling gold came courtesy of Matt Walls in the men's omnium- the first time a male British Olympic cyclist has won the Olympic title in that event. Walls also won a silver medal alongside Ethan Hayter in the men's Madison event.

On the waves, Giles Scott secured Great Britain's sixth consecutive gold medal in sailing's Finn class which was making its final Olympic appearance, while Hannah Mills became Great Britain's most successful female Olympic sailor defending her Women's 470 title with Eilidh McIntyre having won the same class with Saskia Clark in 2016. McIntyre was emulating her father Michael who had won gold in the Star class alongside Bryn Vaile at the 1988 Games in Seoul.

On a less positive note a number of iconic 'streaks' of British success were broken. The men's team pursuit title left British hands for the first time since 2004, as did the men's team sprint with both Ed Clancy and Jason Kenny denied fourth consecutive gold medals in the same event. The men's match sprint in cycling also left British hands for the first time since 2004, although Jack Carlin won a bronze medal. The men's coxless four lost the Olympic title for the first time since 1996, while the rowing team – having won the only British gold medal as part of the disastrous 1996 British Olympic team, and thus maintained Great Britain's streak of at least one gold medal in every Summer Games – won no gold medals for the first time since 1980 winning only 2 medals in total across the whole Olympic rowing regatta.

Despite winning five medals in total, these Olympics were the first time since 1996 that Great Britain's athletics team failed to win a gold medal. This was partly due to unfortunately timed injuries to reigning world champions Dina Asher-Smith (200 metres) and Katarina Johnson-Thompson (Heptathlon) who were seen as Britain's best medal hopes in the athletics events. The men's 4 × 100 metres relay squad were also pipped to gold by Italy by 0.01 seconds on the finish line having been leading going into the anchor leg. However, it subsequently emerged the British quartet could lose their silver medals after a member of the quartet CJ Ujah was revealed on 12 August 2021 to have failed a drugs test with Ujah provisionally suspended by the Athletics Integrity Unit following the games pending further investigation . The matter was referred to the Court of Arbitration For Sport Anti-Doping Division to decide if the British 4 × 100 male quartet should be disqualified from the final results. On 18 February 2022, it was confirmed the British Mens 4 × 100 metres athletics relay quartet would be stripped of their silver medals meaning Great Britains final medal tally from the game is 64 – one less than achieved at the London 2012 Olympics. Three medals across the four middle-distance events, a long hoped-for global medal for Holly Bradshaw in pole vault and a bronze medal for the women's sprint relay team ensured the British athletics team did not leave Tokyo empty handed.

A number of British defending champions from 2016 (including some 'double' champions who won gold medals in 2012 and 2016) either were not selected, or were unable to retain their titles, including Mo Farah, Alistair Brownlee, Jade Jones, Charlotte Dujardin and Andy Murray. In comparison, three former multiple world champions, but long time 'nearly men' on the Olympic stage finally reached the top step of the rostrum, Jonathan Brownlee winning the inaugural triathlon mixed relay, James Guy in both the men's 4 × 200 metre freestyle relay and the mixed medley relay, and Tom Daley, winning gold in the men's 10 metre synchro with debutant Matty Lee, before his bronze in the individual event made him the first British diver to win four career Olympic medals.

Great Britain had some notable success in new sports and events, winning the inaugural gold medals for women's BMX freestyle, mixed 4 × 100 metre medley swimming relay (in a new world record), women's madison and the triathlon mixed team relay, and medals in men's BMX freestyle, women's skateboarding and women's featherweight boxing. The women's +87 kg weightlifting event was technically a new event, but was in reality simply an adjusted version of the existing super-heavyweight class. Nonetheless, Emily Campbell's silver medal was the first ever won in weightlifting by a British woman, the first British weightlifting medal for either sex since 1984 and the first at a non-boycotted Games since Louis Martin medalled in consecutive Olympics in 1960 and 1964. Indeed, the weightlifting event at the Games was a significant success for Great Britain, with top-seven finishes for all four selected lifters, and Sarah Davies coming agonisingly close to winning a second silver medal in the −64 kg class.

Great Britain also had great success in both of the men's and women's modern pentathlon events with Kate French taking gold in the women's event, while Joseph Choong became the first British male modern pentathlete to win an individual medal when taking gold in the men's event. The victories of French and Choong marked the first time since the introduction of the women's event in 2000 that a 'double' had been achieved, with the same nation winning both men's and women's events.

Medallists

| width="78%" align="left" valign="top" |