The Ukrainian president spoke to the Commons via video - the first time a foreign leader has addressed MPs like this - and received a standing ovation.
Speaking to MPs and peers in the Commons, President Zelensky gave a day-by-day account of the invasion by Russia, which began a fortnight ago.
The president also spoke of the 50 children "that could have lived" but were killed by Russian forces, along with those of his people dying from dehydration where their cities had been blockaded by Russia.MPs and peers gathered in the Commons to listen to the address through headsets and watch the president on large screens, the president said he wanted to "remind you of the words Britain heard already, which become current again".
The leader concluded his speech by saying: "Do what you can, do what you must, because greatness obliges greatness, of your state and your people.MPs crammed into every corner. Members of the House of Lords packed the public galleries high in the chamber. Parliamentary staff huddled close to peer through the stone arches, almost in the roof, to watch.
Ukraine's leader told of his country's pain as each day, a war "we did not start" progressed. Bombs falling on schools. Churches destroyed. Children's hospitals attacked. Food and water running low in some parts. Mr Johnson said: "At this moment, ordinary Ukrainians are defending their homes and their families against a brutal assault, and they are by their actions inspiring millions with their courage and their devotion.