MPs rose to their feet and gave a standing ovation to Ukraine's President Zelensky.
In a historic first, a videolink was granted to allow the Ukrainian president to directly address MPs.
They packed the benches of the Commons, and stood and applauded when he appeared on the screen.
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President Volodymyr Zelensky told MPs: "Just the same way you once didn't want to lose your country when the Nazis started to fight your country and you had to fight for Britain. Thirteen days of this struggle ... at 4 o'clock in the morning we were attacked by cruise missiles. Everybody woke up and people with children..."
He added: "We have been fighting for our country, with our army."
He went on: "Russian forces demanded that we lay down arms, we need to continue fighting."
President Zelensky invoked British wartime leader Winston Churchill as he vowed Ukraine "will fight to the end".
Echoing Churchill's famous 1940 "we shall fight on the beaches" speech, Zelensky said: "We will not give up and we will not lose.
"We will fight to the end at the sea, in the air, we will continue fighting for our land, whatever the cost. We will fight in the forests, in the fields, on the shores, in the streets."
Both Boris Johnson and Labour leader Sir Keir Starmer paid tribute to the president himself and the Ukrainian people.
Commons Speaker Sir Lindsay Hoyle said the solidarity of the House of Commons was with him and the people of the Ukraine.
The Prime Minister said: "Never before had the Commons heard such an address. In his righteous defence I believe he has moved the hearts of this House."
Mr Johnson said people in the Ukraine were "inspiring millions by their courage and devotion".
"This is a moment for us to put our political differences aside and I know I speak for the whole House when I say that Britain and our allies are determined to press on, to press on with supplying our Ukrainian friends with the weapons they need to defend their homeland as they deserve, to press on with tightening the economic vice around Vladimir Putin, and we will stop importing Russian all. We will employ every method we can, diplomatic, humanitarian and economic."
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