Ban Ki-moon, the UN secretary-general, led calls for Myanmar to make good on the agreement to let outsiders into the country.
Three weeks after cyclone Nargis hit the Irrawaddy delta, the UN says that three in four of those most in need of aid have yet to receive any help.
About 2.4 million cyclone survivors are still short of food, water and shelter and many are at risk of dying from hunger or disease.
Ban called the conference an "important exercise for building greater trust and co-operation" between Myanmar and the outside world.
The European community, which has already pledged $72.5m, offered another $26.8m.
China boosted its pledge to $11m.
Australia promised $24m, the Philippines doubled its previous pledge to $20m, and South Korea said it would give a total of $2.5m.
In comments echoed by most nations, Ban rejected Myanmar's insistence that the emergency relief phase was over and that it was now time to focus on rebuilding the devastated areas of the Irrawaddy Delta.
"I expect the relief effort will run for several months, probably six months at least, as we feed and care for those who have lost everything," Ban said to open the meeting.
Ban is the first UN secretary-general to visit Myanmar in more than four decades.
The United States said it was ready to offer more than the $20.5 million of aid sent after the May 2 cyclone.
Scot Marciel, a US envoy to south east Asia said, "However, in order to do so, the government must allow international disaster assistance experts to conduct thorough assessments of the situation."
"The United States is prepared to offer much more, and we know that we must act quickly to prevent further loss of life," Marciel said.
General Thein Sein, Myanmar's prime minister, thanked the 500 delegates from 50 countries for their help so far.
He said more aid would be welcome as long as it came from "genuine goodwill" and "provided that there are no strings attached nor politicisation involved".
China and some other Asian countries said it was important to keep aid and politics separate in dealing with the reclusive country.
However, the military government is looking to the longer term, saying it needs around $11bn for resettlement, reconstruction and rehabilitation.
"There was a very clear message from the participants at the conference that they want to see the promises that have been made translated into reality," said John Holmes, the UN's top emergency relief official.
Than Shwe, Myanmar's senior general, promised Ban on Friday that all foreign aid workers will be let in.Constitution 'approved'
Voters in cyclone-hit areas of Myanmar have approved a constitution, in a referendum held in the Irrawadday delta and Yangon, state media reported.
Almost 93 per cent of those voting are said to have approved the constitution.
Local media also said that some 4.5 million voters were eligible to cast ballots in the cyclone zone.
A first round of voting had been held on May 10 in regions spared by the storm.
Nationwide, state media said the constitution was approved by 92.48 per cent, with a 98 per cent turnout.
Critics say the document was drafted under the direction of the ruling military and ensures that the generals will have the final say in running the country.
The constitution would bar Nobel Peace Prize laureate Aung San Suu Kyi, the detained leader of the country's pro-democracy movement, from public office.