The 37-year-old will also hope to tee up a spectacular final duel between two fellow legends in Ethiopia’s Kenenisa Bekele and world record holder Eliud Kipchoge of Kenya.
Farah last year gave up plans of running the marathon at the Tokyo Olympics and will instead compete in the 10,000 metres which, if successful, will be his fifth gold medal at the Games.
This year’s London Marathon has been affected like all sports by the coronavirus pandemic and was postponed from the original date of April 26.
It is also the first time it will be only contested by elite athletes with the 45,000 casual runners prevented from doing so due to the coronavirus.
World Athletics will lift its suspension of the Olympic qualification system for marathon races from September 1, meaning athletes have the chance to achieve the Olympic standard of two hours 11 minutes 30 seconds.
“The London Marathon has been so important to me since I was a schoolboy and when they asked me to do this I thought it would be great to help,” said Farah, who was third in the 2018 London Marathon.
“I am in good shape, I’ll be in London that week and it fits in with my training.
“I’ve been training with some of the British guys who are going for that Olympic qualifying time and they are good lads.
“I know just how special it is to compete for your country at an Olympic Games and it would be great to help other athletes achieve this.
“With the current global situation and lack of races, the London Marathon in October is the best chance for athletes to run the Olympic qualifying time.”
London Marathon director Hugh Brasher said the six-time track world champion’s decision to act as pacemaker was a “wonderful gesture”.
Download our app and read this and other great stories on the move. Available for Android and iOS.