Theresa May’s government has been thrown into chaos after the Commons overwhelmingly rejected her Brexit deal.
In a blow to the prime minister’s authority, MPs voted 432 to 202 - a majority of 230 - against the withdrawal agreement she reached with Brussels after more than two years of negotiations.
May - who told MPs she would "listen" to the result - will now face a vote of no confidence on Wednesday after the Labour leader Jeremy Corbyn pressed ahead with his plan to oust the prime minister and trigger a general election.
Both Labour and the SNP had surprised Parliament by dropping their planned amendments to the Government motion, thereby allowing MPs to train all of their fire on the Brexit deal.
May will now have to return to Parliament with a new plan by Monday night if she is to stand any chance of saving her Brexit vision.
The defeat – which dramatically increases the chances of a no-deal Brexit – came after the Prime Minister had made a last-ditch attempt to win over MPs to her cause.
Closing five days of Commons debate, she told a packed chamber that it was a chance for MPs to back "unity over division".
She said: "This is the most significant vote that any of us will ever be part of in our political careers. After all the debate, all the disagreement, all the division, the time has now come for all of us in this House to make a decision.
"A decision that will define our country for decades to come. A decision that will determine the future for our constituents, their children and they’re grandchildren. A decision that each of us will have to justify and live with for many years to come. We know the consequences of voting for this deal, they are laid out in black and white in the pages of the withdrawal agreement.
"But no one who votes against this deal will be able to tell their constituents what real world outcome they voted for, because a vote against this deal is a vote for nothing more than uncertainty, division and the very real risk of no-deal or even no Brexit at all.”
Earlier, attorney general Geoffrey Cox had told MPs the agreement “provides for the orderly and predictable and legally certain winding down of our obligations and involvement in the legal systems of the EU”.
He added: “If we do not legislate for that legal certainty as a matter of law alone, thousands of contracts, thousands of transactions, thousands of administrative proceedings, of judicial proceedings in the European Union and this country, will be plunged into legal uncertainty.
“It would be the height of irresponsibility for any legislator to contemplate with equanimity such a situation.
"If you were a litigant in a court, if you were dependent upon having concluded a contract on the basis of EU law and you found yourself suddenly with the rug pulled from under you, not knowing what your legal obligations would be, you would say to this House: 'What are you playing at? What are you doing? You are not children in the playground, you are legislators.' We are playing with people's lives."
But Labour leader Jeremy Corbyn said the withdrawal agreement was "a bad deal for our economy, a bad deal for our democracy, and a bad deal for Britain", which his party could not support as he repeated his calls for a general election.
He said: "Under this government more people are living in poverty, including half a million more children. Homelessness has risen every year; too many people are stuck in low paid and insecure work; too many people are struggling to make ends meet and falling into debt.
"Nothing in this Brexit deal – and nothing on offer from this government – will solve that."