Nigel Farage’s final speech as an MEP saw him reprimanded for saying his party “just hate the EU” in the wake of a discussion about Auschwitz.
His jeering colleagues were told to “put your flags away – you’re leaving” by the chair of the proceedings.
Meanwhile mourning Remainer MEPs sang Auld Lang Syne and held aloft scarves bearing the words “always united” as the European Parliament ratified Boris Johnson’s deal in Brussels and Brexit became officially unstoppable.
The display came after the parliament marked 75 years since the liberation of Auschwitz.
Farage described the vote as “the point of no return”.
Widely anticipated after Westminster backed the withdrawal agreement earlier this month, it means the UK will leave the EU at 11pm on Friday and British MEPs will effectively lose their jobs.
The historic moment, which ends 47 years of Britain’s membership of the bloc, led to emotional scenes in the chamber.
Remainers voiced hopes that the UK would rejoin the EU in future and broke into a rendition of the farewell folk song Auld Lang Syne as the vote was declared.
Ursula von der Leyen, president of the European Commission, led the debate and paid tribute to Britons to the EU, adding “we will always love you and we will never be far” as she bid UK MEPs farewell.
“No new partnership will bring back the benefits of being part of the same union but we have the duty to seek the best for the British and for the European people in a post-Brexit world,” she said.
“To our British friends and many – perhaps not all – but many of our British MEPs here in the room, I want to use the words of the famous British poet George Eliot.
“She said, ‘Only in the agony of parting do we look into the depth of love’.
“We will always love you and we will never be far, long live Europe.”
Belgian MEP Guy Verhofstadt, who chairs the parliament’s Brexit steering group, paid tribute to British MEPs’ “wit, charm, intelligence” and “stubbornness” – and predicted the UK would rejoin.
He said: “It is sad to see a country leaving that twice liberated us, has twice given its blood to liberate Europe.
“I can only say, we will miss you. This vote is not an adieu. This vote is only, in my opinion, an au revoir.”
But Farage was defiant, telling the chamber that Friday “marks the point of no return”.
He said: “This is it, the final chapter, the end of the road, a 47-year political experiment that the British frankly have never been very happy with,” the Brexit Party MEP said.
“I’m not particularly happy with the agreement we’re being asked to vote on tonight but Boris has been remarkably bold in the last few months and, Ms Von Der Leyen, he’s promised us there will be no level playing field and on that basis I wish him every success in the next round of negotiations.
“What happens at 11pm this Friday, January 31, 2020, marks the point of no return. Once we’ve left we are never coming back and the rest, frankly, is detail.
“We are going, we will be gone and that should be the summit of my own political ambitions.”
Meanwhile, back in London, Brexiteers are preparing to celebrate Brexit on Friday with a party in Parliament Square.
Johnson will now embark on trade deal negotiations with Brussels, with both sides hoping to agree on a future relationship by the end of the transition period in December.
After the speeches, Brexit Party MEPs shared a round of drinks at the bar in the European Parliament in Brussels.
MEP Martin Daubney posted a video from the bar, tweeting: “It’s a carnival atmosphere for jubilant Brexiteers.”