Ukrainian President Volodymyr Zelensky will address British politicians via video link later, as his country battles the Russian invasion.
Mr Zelensky’s speech will be broadcast to MPs in the Commons at 17:00 GMT using TV screens being installed in the chamber.
Members of the House of Lords are also expected to watch from the public gallery.
MPs will be able to follow a live translation over special headphones.
After Mr Zelensky’s speech, Boris Johnson and Labour leader Sir Keir Starmer will respond.
Meanwhile, the prime minister is hosting meetings in London with the leaders of Poland, Hungary, Slovakia and the Czech Republic.
The series of meetings will be to discuss the UK’s support for security in central Europe.
Commons Speaker Sir Lindsay Hoyle said: “Every parliamentarian wants to hear directly from the president, who will be speaking to us live from Ukraine, so this is an important opportunity for the House.
“Thanks again to our incredible staff for working at pace to make this historic address possible.”
His counterpart in the House of Lords, Lord McFall of Alcluith, said: “Today we are not members of the House of Lords or Commons, we are parliamentarians, united in solidarity with Ukraine.”
Mr Zelensky, a former comedian and actor, has been the figurehead of Ukraine’s struggle since Russian President Vladimir Putin’s forces invaded the country last month.
Last week, he received a standing ovation when he spoke, via videolink, to the European Parliament.
Mr Zelensky has also spoken frequently to Prime Minister Boris Johnson since the conflict started.
On Monday, the president promised to punish anyone who commits atrocities against the Ukrainian people.
“There will be no quiet place on Earth for you, except for the grave,” the president said.
On Monday evening, Mr Johnson spoke with US President Joe Biden, French President Emmanuel Macron and German Chancellor Olaf Scholz, with the four leaders agreeing to maintain pressure on Russia to isolate Mr Putin diplomatically and economically.
“The prime minister stressed that our goal must be ensuring Putin’s failure in this act of aggression against Ukraine,” said a No 10 spokeswoman.
At Prime Minister’s Questions last week, MPs stood to applaud Vadym Prystaiko, Ukraine’s ambassador to the UK, who watched parliamentary proceedings from the Commons gallery.