The 2020 London Marathon was originally scheduled to be held on 26 April but was postponed until 4 October due to the COVID-19 pandemic.

[2] On 6 August, it was confirmed that the marathon would go ahead as an elite-only race, with the mass participation event cancelled.

All athletes were tested for COVID-19 multiple times before the race,[5] and wore face coverings and observed social distancing when not competing.

[1] The 2021 London Marathon was postponed from April until October 2021, to maximise the chance of being able to hold a mass participation event.

[10] The men's race also featured Mosinet Geremew, Mule Wasihun,[8] Sisay Lemma, and Tamirat Tola, all of whom had personal best times under 2:05.

[13] American Galen Rupp, who won his country's Olympic qualifying event in February 2020, did not compete, after undergoing surgery for an existing injury.

[8] All of the races were run in heavy rain due to Storm Alex,[21] which made them the wettest London Marathon in history.

[7] Ruth Chepng'etich was running second until she was overtaken by Sara Hall around 150 metres (490 ft) from the finish line.

[21] Hall's second place was the first time that an American had finished in the top three of the London Marathon since 2006, when Deena Kastor won the race.

[7] The men's wheelchair race was won by Canadian Brent Lakatos in a sprint finish involving six athletes.

[15] David Weir and Marcel Hug finished second and third respectively,[26] and Sho Watanabe, Jordi Madera, and Kota Hokinoue were also involved in the final sprint.

[27] Lakatos was the first Canadian to finish on the podium in the London Marathon men's wheelchair event for 10 years.

[15] The women's wheelchair was won by Nikita den Boer, who finished 82 seconds clear of pre-race favourite Manuela Schär.

[15] Den Boer beat her previous personal best by over 10 minutes, and due to her victory, she qualified for the delayed 2020 Summer Paralympics.

[31] In January 2021, the virtual event received a Guinness World Record for most users to run an organised remote marathon in 24 hours.