London Marathon will become a one-off, two-day event in 2027, expanding the weekend to host a record 100,000 participants across April 24 and 25.

A projected 1.34 million people entered the 2027 ballot, with the prior year drawing 59,830 finishers and charities raising over £90 million in 2026.

The two-day format is designed to meet unprecedented demand and aims to raise more than £150 million for charity while delivering substantial social and economic benefits.

Successful execution depends on collaboration among the mayor, route councils, emergency services, and other stakeholders.

Elite events will be spread across the two days, featuring elite women, para-athletes, championship, and good-for-age runners on one day and their male counterparts on the other, with exact scheduling to be announced.

Details on which specific groups compete on which day will be confirmed later as the plan is refined.

The elite and championship events will lead the mass participation on alternating days, with full format details to come in the months ahead.

Ballot entrants will be notified in early July, and participants may run on only one of the two days.

The two-day event is a one-year trial conceived years ago and contingent on permissions and logistics.

The expansion seeks to meet record demand and amplify fundraising and social impact beyond the traditional one-day format.

Approvals from local authorities, emergency services, councils, and the Mayor were required; The Guardian first reported the plan in March 2026.

Participants will run only once during the weekend, with July ballot results and the event billed as a once-in-a-generation reimagining of a city-wide celebration.