A one-off expansion of the world’s biggest marathon will see 100,000 participants take to the capital’s streets over two days, with organizers predicting record charity fundraising and a £400m social and economic impact.
London Marathon Events has confirmed that the TCS London Marathon will expand to become a two-day event for 2027.
As a result of this one-off format change next year, the London Marathon, already the most famous marathon on the planet, will become a spectacular two-day event on April 24-25. The expanded event will further increase the global impact of the event, which in 2025 was recognized as the #1 marathon brand in the world.
The unique Double format will welcome 100,000 participants over two days, all following the same iconic route from Greenwich to Westminster in what will be an unprecedented weekend of sport, charity and community celebration.
By extending the event by two days, the Double is creating more opportunities than ever to be part of the London Marathon. It will allow a record number of participants to take part in a single marathon, helping to meet the extraordinary demand for places, highlighted by 1.33 million people taking part in next year’s event.
Dublin will also create the biggest fundraising moment in UK sport. Already the world’s largest one-day annual fundraising event, with more than £90m raised for charity by 2026 participants to date, this two-day marathon will give more charities more opportunities to raise vital funds.
Elite women, elite female para-athletes, championship and ‘age-good’ women will headline the mass event on one day, and elite men, elite male para-athletes, championship and ‘age-good’ men on another. All details of the format will be confirmed in the coming months.
All those who have already applied to participate next year will vote on both Saturday and Sunday. On both days, participants will not be allowed to take part in the event in person, although they will be able to complete the London Marathon on one day and the London Marathon MyWay virtual event on the other day.
Voting results will be announced in early July, seats will be allocated randomly.
Organizers say the 2027 TCS London Marathon Double will be “a city-wide celebration of sport, music and community, with charity partners, creatives and neighborhood groups shaping the activities across two days”.
A dual focus will be on inspiring and supporting the next generation. Every London school will receive two guaranteed entries for teachers or staff, recognizing that the spark to activism often starts in the classroom.
All additional revenue generated by the Double will be donated by the London Marathon Fund to projects that inspire children and young people across London and the UK.
To ensure local community participation, additional guaranteed entries have also been allocated to each London borough along the route, enabling grassroots groups and charities to attend and benefit from the expanded event.
The Double will cap off a full week of TCS London Marathon celebrations, starting with an enhanced London Marathon Run Show and featuring the London Marathon & Friday Night Lights 5km. The week will also include the TCS Mini London Marathon, the world’s largest one-day hour-long children’s event, which will take place in 2027 on Friday 23 April and will welcome more than 20,000 young participants.
London Marathon Events CEO Hugh Brasher said: “The 2027 TCS London Marathon Double is our most ambitious evolution to date; a once-in-a-generation, once-only event, redefining what a marathon and an entire city of activities can be.
“By expanding to 100,000 runners over two days, we’re opening the door for more people, more charities and more communities to take part in the world’s biggest marathon. We believe that over £150m could be raised for good causes and the UK economy would have a £400m social and economic benefit.
“We are grateful for the vision and support of the Mayor of London, the route councils, the emergency services and all the stakeholders involved who have given their support to make this world-first event possible for London and the UK.”
Mayor of London Sadiq Khan added. “London is the sporting capital of the world and I am delighted that for one year only, in 2027, the world-renowned TCS London Marathon will be expanded into a two-day event.
“This unique, one-off double will see a record 100,000 participants take part over two days, creating the biggest fundraising moment in UK sporting history and supporting the work of so many incredible charities.
“The London Marathon showcases the best of our capital and we will continue to work closely with London Marathon Events and our partners to ensure appropriate measures are in place throughout the weekend as we build a better, more prosperous London for everyone.”
Brasher insists that will also be a one-off. As he told the media in April, “It will be one and done.”
The idea of two full days dominating the London Marathon in 2027 is highly ambitious, but Brasher says he was inspired by a Robert Browning quote that his father, London Marathon founder Chris Brasher, was fond of:
Despite the idea being mooted publicly earlier this year, the London Marathon has been working hard to get its many and varied stakeholders on board with the idea. These range from the police and transport networks to the Mayor and the London Boroughs.
The implementation of the idea has also been approached with caution, as Brasher explained earlier this year. “You have to bear in mind that the London Marathon has been running for 45 years and it’s at the love seat, not just of the sporting calendar but of the London calendar.
It’s also the perfect time for London to do this ambitious Double. One of the original founding pillars of the London Marathon was to show some joy and happiness to a somewhat troubled world. “And those words ring truer in 2026 than they did in 1981,” Brasher says.
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In the age of social media and artificial intelligence, Brasher also feels that people are likely to continue to seek out real-life moments and experiences, such as running London, more and more.
