Macmillan Cancer Support’s first Go Sober for October campaign raised £2.3m.
The charity said 31,669 people, known as sober heroes, signed up to stop drinking alcohol during October and raised funds for Macmillan.
Macmillan said the campaign was helped by a strong social media presence that offered support and encouragement. Fundraising tools were also offered to boost donations, including 'golden tickets', which allowed participants to buy a night off for a special occasion for a minimum donation of £15.
The campaign was launched in partnership with the Australian organisation Dry July, which has raised A$15m – about £8.1m – since 2008.
A spokeswoman for Macmillan said the campaign had surpassed expectations, but she would not say what its fundraising target had been.
Lynda Thomas, director of fundraising at Macmillan, said: "We are overwhelmed with the fantastic reaction and the huge amount of money raised, which will help us ensure no one faces cancer alone.
"The level of sponsorship reflects what a real challenge this was for those taking part – some even joked that it would have been easier to climb a mountain or run a marathon."
About 35,000 people raised more than £4m last year for Cancer Research UK’s first Dryathlon, which challenges social drinkers to take a month-long break from alcohol during January.
The CRUK campaign has returned this month with participants, known as dryathletes, encouraged to get sponsored by friends and family, or pledge money they have saved by abstaining from alcohol.