Almost £7bn has been raised to immunise 300 million children at a virtual global vaccine summit hosted by the UK.
Prime Minister Boris Johnson said up to eight million lives would be saved as a result of the funds pledged at the Gavi vaccine summit on Thursday.
The money will help immunise children against diseases like polio, diphtheria and measles over five years.
Mr Johnson said the triumph of humanity over disease was the "greatest shared endeavour of our lifetimes".
The summit raised funds for Gavi, a global alliance of public and private sector organisations promoting vaccination among the world's poorest communities.
Pledges by more than 50 countries and individuals like billionaire philanthropist Bill Gates saw the total surpass an initial target of $7.4bn (almost £6bn).
Mr Gates donated $1.6bn (£1.3bn) from his foundation and Mr Johnson pledged £1.65bn over the next five years, making the UK the organisation's biggest donor.
The summit comes as the world continues to struggle to get to grips with the coronavirus pandemic.
Mr Johnson also used the conference to urge world leaders to renew their "collective resolve" to find a Covid-19 vaccine.
"Just as we have great military alliances like Nato... where countries collaborate on building their collective military defence, so we now need that same spirit of collaboration and collective defence against the common enemy of disease," he said.
"It will require a new international effort to co-operate on the surveillance and the sharing of information - data is king - that can underpin a global alert system, so we can rapidly identify any future outbreak. And it will mean a radical scaling-up of our global capacity to respond."
International Development Secretary Anne-Marie Trevelyan later said she believed the UK was capable of delivering a coronavirus vaccine to those who need it "at speed" when one becomes available.
Analysis: Trump's surprise appearance
By Tulip Mazumdar, global health correspondent
US President Donald Trump made a surprise appearance at the virtual global vaccine summit.
Last week, Mr Trump severed ties with the UN's health agency, the World Health Organization, stopping around $400m (£317m) in support, after accusing it and China of mishandling the outbreak.
There was international criticism of the decision, particularly because it was made in the middle of a global pandemic.
But at the summit, Mr Trump struck a different tone in what was a very brief and seemingly very off-the-cuff, pre-recorded message.
"As the coronavirus has shown, there are no borders, it doesn't discriminate," he said.
"It's mean, it's nasty but we're going to take care of it together.... We will work hard, we will work strong... good luck, let's get the answer."