100K ultra runs in London
Find 100k ultra runs near me in London for 2025/2026 - search by date or place, display on a map or use the advanced search to find your perfect race.
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Click an event for full event details, location, route, sustainability, what's included and how to enter.

- Sat 24 May
- £199
- Entries close today
- Sat 24 May
- £199
- Entries close today
London 2 Brighton Ultra Challenge | Full 100km Continuous
Leafy Richmond to sunny Brighton – over the North Downs and the South Downs, with some wonderful Surrey and Sussex countryside in between, fully supported all the way with a huge celebratory finish!
- Chip timing
- Enter online
- GPS tracking
- Hilly
- Age 18 & over
- 100 km trail running + 1500 m ascent

- Sat 24 - Sun 25 May
- £199
- Entries close today
- Sat 24 - Sun 25 May
- £199
- Entries close today
London 2 Brighton Ultra Challenge | Full 100km over 2 days
Leafy Richmond to sunny Brighton, over the North and South Downs, with some wonderful Surrey and Sussex countryside - all in daylight hours and with a good nights' sleep mid-way!
- Chip timing
- Enter online
- GPS tracking
- Undulating
- Hilly
- Age 18 & over
- 100 km trail running + 1500 m ascent

- Sat 13 - Sun 14 Sep
- £199
- 18 charities
- Sat 13 - Sun 14 Sep
- £199
- 18 charities
Thames Path Ultra Challenge | Full 100km Continuous
The full, non-stop option of the epic Thames Path Challenge from leafy South West London following the river to Hampton Court, Runnymede to finish at Henley-on-Thames for a celebratory finish and BBQ!
- Chip timing
- Enter online
- GPS tracking
- Flat
- Undulating
- Age 18 & over
- 100 km trail running + 350 m ascent

- Sat 13 - Sun 14 Sep
- £199
- 18 charities
- Sat 13 - Sun 14 Sep
- £199
- 18 charities
Thames Path Ultra Challenge | Full 100km over 2 days
An epic challenge from leafy South West London on the River Thames featuring Hampton Court, Runnymede of Magna Carta Fame, Henley-on-Thames and a fabulous celebration finish - all in daylight.
- Chip timing
- Enter online
- GPS tracking
- Flat
- Age 18 & over
- 100 km trail running + 350 m ascent