The Prime Minister was confronted over the controversial move as he insisted to MPs it was necessary to protect the nation’s finances.
Spending 0.7 per cent of GDP was written in law and was restated in the 2019 Conservative manifesto, only to be abandoned by the UK Government due to coronavirus.
Chancellor Rishi Sunak then set out a test to restore it as a “compromise” if the Office for Budget Responsibility (OBR) believed the UK was not borrowing to finance day-to-day spending and underlying debt is falling.
The UK Government won 333 to 298 after a vote in the Commons on Tuesday afternoon.
Earlier Theresa May revealed she would rebel for the first time, telling MPs the cut meant the Government “turns its back on the poorest in the world”.
The former Prime Minister said: “This isn’t about palaces for dictators and vanity projects, it’s about what cuts to funding mean – that fewer girls will be educated, more girls and boys will become slaves, more children will go hungry and more of the poorest people in the world will die.
"We made a promise to the poorest people in the world, the Government has broken that promise. This motion means that promise may be broken for years to come."
Having only happened once in the decades prior, the Tory rebels described it as a “trap” to keep the cut.
Tory MP Andrew Mitchell claimed the plan put forward by the Treasury was “no compromise at all” but instead “a fiscal trap for the unwary”.
He warned that the Government was “trashing our international reputation” and the measure would have an “enormous impact on our role in the world and above all on the huge number of people who will be very severely damaged, maimed, often blinded and, indeed, die as a result of these cuts”.
Mr Mitchell added: “Anyone who thinks this is not affecting our party’s reputation is living in cloud cuckoo land.
“There is an unpleasant odour wafting out from under my party’s front door.”
The SNP International Development spokesperson Chris Law MP claimed the cuts showed "Scotland's values are increasingly under attack at Westminster".
He added: "Scotland completely rejects Tory cuts to international aid, which go against our values and will push some of the poorest and most vulnerable people in the world even further into hardship."It is shameful that Boris Johnson is pressing ahead with these cuts. Not only is he breaking his own Tory manifesto commitment, and riding roughshod over the UK's moral and legal responsibilities, but he is doing it at the worst possible time - during a global pandemic."
Speaking after the vote, the Chancellor Rishi Sunak tried to reassure MPs.
He said: “I want to commit to the House that both I and the Prime Minister and the Foreign Secretary will continue to work with all MPs on how we can continue to be a global leader helping the world’s poorest, on how to improve our aid spending, target it most effectively and ensure that it is getting to those who need it most."