The 2027 TCS London Marathon will split across Saturday, April 24 and Sunday, April 25, marking the first two‑day edition of the race. Elite women and para‑athletes will lead the Saturday mass start, while elite men and their para‑counterparts will front Sunday. Organisers promise a seamless format, with final details due later this year.

Running the event over two days allows 100,000 runners to line the streets, a record field that responds to the 1.33 million ballot entries for next year's race. CEO Hugh Brasher projects the expansion could generate more than £150m for charities and deliver a £400m boost to the UK economy, underscoring the marathon’s growing social impact.

Mayor Sadiq Khan praised the move as a one‑off celebration of London’s sporting stature. By accommodating a larger crowd, the marathon aims to deepen community involvement and reinforce its reputation as the world’s premier city marathon.