Rob Reynolds, Al Jazeera's correspondent in Haiti, said: "The pledge to cancel debts comes as the World Bank and IMF are also working on wiping the slate clean on Haiti's debt - a debt that this country is in no position to pay.
"Most importantly, going forward, the international community and G7 ministers say any future funding for Haiti's recovery will come in the form of grants and not loans that have to be repaid over time."
Haiti says that more than 200,000 people died in the January 12 earthquake, which displaced hundreds of thousands more.
Aid has come from around the world but so much of Haiti's infrastructure was lost or damaged that officials say it will take a wholesale reconstruction effort to get the country on its feet economically.
Gordon Brown, the British prime minister, hailed the G7 decision, saying "a nation buried in rubble must not also be buried in debt".
"The UK has already cancelled all debts owed to it by Haiti and I strongly welcome today's G7 commitment to forgive Haiti's remaining multilateral debt.
Timothy Geithner, the US treasury secretary, endorsed the position on Saturday: "The earthquake in Haiti was a catastrophic setback to the Haitian people who are now facing tremendous emergency humanitarian and reconstruction needs, and meeting Haiti's financing needs will require a massive multilateral effort.
"Today, we are voicing our support for what Haiti needs and deserves - comprehensive multilateral debt relief."
There have been persistent problems in getting aid to the more than one million Haitians left homeless after the 7.0-magnitude quake which levelled much of central Port-au-Prince and surrounding towns.
Rescue operators struggled to get aid out to earthquake victims and many aid groups called for greater co-ordination.
During his visit to Port-au-Prince on Friday, Bill Clinton, the former US president, apologised for delays in getting aid to the survivors.
"I'm sorry it's taken this long ... I'm trying to get to what the bottlenecks are, part of it is just shipping the volume of food in here that is necessary."