International donors have pledged 1.1 billion US dollars (£860 million) for war-torn Yemen, the UN secretary-general said.
Antonio Guterres appealed to the fighting sides to grant access to humanitarians and revive diplomatic efforts to end a conflict that has killed over 10,000 civilians.
He ended a day-long Yemen aid conference by hailing the "clear generosity and solidarity" of governments and civil society after two years of intensified conflict in the Arab world's poorest country.
The conference, co-sponsored by the United Nations, Switzerland and Sweden, raised pledges for over half of the 2.1 billion dollars (£1.64 billion) sought by the UN this year in an appeal that was only 15% funded previously.
After years of shortfall in funding for Yemen, Mr Guterres praised a "very encouraging signal" that the target could be met this year.
He said the pledges must now be "translated into effective support" for Yemenis.
"We basically need now three things: Access, access, access," for humanitarian actors to reach all Yemenis in need, he said.
The war has pushed Yemen to the brink of famine, obliterated the health system, led to broad human rights violations and impeded imports of crucial food, resources and medicines.
Aid groups want improved access to civilians, a halt to deadly airstrikes by a Saudi-led, US-supported coalition that has been fighting Shiite rebels known as Houthis, and more respect for international law.
UN officials say the world's largest humanitarian crisis is in Yemen, where 17 million people are classified as food insecure, with seven million of those facing critical food shortages.
The war pits the coalition of mostly Sunni Arab countries against the Iran-backed Houthis and allied army units loyal to a former president.
The Houthis seized the capital, Sanaa, and other areas in 2014, forcing the internationally-recognised government to flee.
Unlike the Syria war, Yemen's conflict has not produced a flood of refugees - making it a relatively contained crisis that has made fewer international headlines.
Violence and administrative blockages have impeded the flow of aid and resources into the country.
Epitomising the daily struggle for Yemenis, dozens of hospital patients in the contested city of Taiz protested on Tuesday against alleged seizures of medical supplies by rebels who control the area, said Fahmi al-Hamami, a physician at the Thawra Hospital.
A preliminary breakdown provided by the UN showed that the UK pledged more than 173 million dollars (£135 million), Saudi Arabia pledged 150 million dollars (£117 million) and the United Arab Emirates, a key member of the coalition, pledged 100 million dollars (£78 million).
The United States said it was committing nearly 94 million dollars (£73 million) in additional assistance, bringing its total to 526 million dollars (£410 million) since the 2016 fiscal year.
Mr Guterres and many diplomats acknowledged aid is only a stopgap measure, insisting that ultimately Yemen's suffering will only ease with a political solution that ends the war.
"On average, a child under the age of five dies of preventable causes in Yemen every 10 minutes," Mr Guterres said at the conference opening.
"This means 50 children in Yemen will die during today's conference, and all of those deaths could have been prevented.
"We are witnessing the starving and the crippling of an entire generation.
"We must act now to save lives."
The United Nations' humanitarian aid co-ordination agency, OCHA, says some 18.8 million people need humanitarian or protection assistance in Yemen.
By contrast, the UN refugee agency says war-depleted Syria has some 13.5 million people in need.
"In simple terms, the situation in Yemen is catastrophic," Geert Cappelaere, Unicef's director for the Mideast and North Africa, told The Associated Press.
"There is no single country in the world where, today, children are more suffering than in Yemen."
The conflict threatens to endanger access to the Hodeida port on the Red Sea, a vital lifeline for most of Yemen's population.
UN officials say a feared Saudi-led attack on the port would displace up to 500,000 people and require additional humanitarian aid of up to 85 million dollars (£66 million).
Russian deputy foreign minister Gennady Gatilov expressed concerns about "worrying rumours of an assault on Hodeida", and called for an "immediate lifting" of the Saudi-led sea and land blockade.
Speaking in Beirut, Mr Cappelaere said Unicef and other aid groups have called on all parties to keep the port and other entry points, such as the Sanaa airport, open on a daily basis to bring in much-needed supplies.
Fewer than 45% of health facilities are now fully functioning, and the flow of "essential medicines" has fallen by nearly 70%, said World Health Organisation Director-General Margaret Chan.
"Health needs go well beyond the prevention of outbreaks," she said in a statement.
"Conditions like diabetes, high blood pressure and cancer are killing more people than bullets and bombs."
The UN appeal this year offers a striking contrast to estimates that the fighting sides have spent untold billions to boost their arsenals for the Yemen war.
Advocacy groups have taken issue with governments like the US and Britain - major contributors at Tuesday's conference - which at the same time have authorised high-tech weapons sales to Saudi Arabia and other regional powers involved in the fight.
Non-governmental groups that have done much of the heavy lifting in Yemen joined the call for greater aid funding.
Robert Mardini, Middle East director for the International Committee of the Red Cross, said needs go beyond physical and financial aid.
"There needs to be clear humanitarian leadership.
"A clear humanitarian voice saying 'enough is enough. End the suffering'," he told conference attendees.
Alex Ventura, emergency co-ordinator for Yemen at Doctors Without Borders, told reporters on Monday that "no one" - aside from his group and the Red Cross - among major aid agencies had full teams in Yemen.
"We need the mainstream (agencies) to change their way of working to be able to be closer to the community, and provide what is needed," he said.