Disaster Emergency Committee chief executive Brendan Gormley said the public response had been "absolutely overwhelming".
A grateful Prime Minister Gordon Brown sought to reassure donors that their "money would get through" to those in need.
He also pledged the UK would not walk away from "a country which has suffered so many disasters" with only "a week's charity".
Outlining the trebling in aid, International Development Secretary Douglas Alexander said: "The international community is dealing with an almost unprecedented level of devastation".
Money so far pledged by the Department for International Development (Dfid) has been used by the Haitian Red Cross to help 20,000 families.
Frederick Wooldridge was a keen skier and mountaineer
Funds have also been used to deploy UK search and rescue teams and by the World Food Programme to transport and organise relief.
The DEC, an umbrella group of 13 major British-based charities, said charities were facing "a huge challenge" but water supplies and medical expertise were "increasingly reaching" people.
It said Oxfam had installed four water tanks capable of holding 10,000 litres of water each since Sunday, and charity Merlin was sending a surgical team of 12.
A £25 donation buys a kit of household essentials, £50 is enough to feed a family for a fortnight and £100 funds temporary shelter for two families, it said.
The DEC appeal for victims of the earthquake in Haiti
Relief efforts have been hampered by supply bottlenecks, leading to security concerns over looting and violence amid increasing desperation.
There are concerns about the safety of aid workers - with reports of gunfire - and some charities have taken security guards.
The DEC said it was monitoring the security situation, but based on the information it had, "isolated incidents" were not interfering with the arrival and distribution of aid.
It is unclear how many Britons remain unaccounted for in Haiti after the earthquake.
The leading US general in Haiti, Ken Keen, said it was a "reasonable assumption" that up to 200,000 people may have died.
Steven Fisher, the UK's ambassador to Haiti and the Dominican Republic, said the Foreign Office's rapid deployment team was "doing quite well" in its efforts to account for expatriate Britons but visiting sites was taking "an awful lot of effort".
DEC APPEAL
The Disasters Emergency Committee is co-ordinating an appeal to help the people of Haiti
There are 13 charities involved including the British Red Cross, Islamic Relief and World Vision
Donate via the
DEC website
or by telephoning 0370 60 60 900
However, one British survivor - bank worker Alistair Cameron, from Inverness - disputed reports access was such a problem.
"Where there was a blockage due to fallen trees or masonry from collapsed buildings, I always found, without too much difficulty, an alternative route," he said.
The Foreign Office said it was beginning to repatriate UK nationals.
Mr Wooldridge was a senior political affairs and planning officer at the UN, for which he had worked in Geneva and Liberia before moving to Haiti in 2007.
A family statement said he had "loved" his work and "had many friends in the UN and beyond".
Another UN worker, Ann Barnes, 59, of Leigh-on-Sea, Essex, is feared to have been killed in the collapse of the headquarters in the capital.
One-Minute World News
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The international community is dealing with an almost unprecedented level of devastation.
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