The visitors were greeted at the train station by Ukrainian Foreign Minister Andrii Sybiha and the president's chief of staff Andrii Yermak.
Among them were European Commission president Ursula von der Leyen and Canadian Prime Minister Justin Trudeau.
In a post on social media platform X, the European commissioner wrote that Europe was in Kyiv "because Ukraine is in Europe".
"In this fight for survival, it is not only the destiny of Ukraine that is at stake. It's Europe's destiny," she wrote.
The guests, also including European Council president Antonio Costa as well as the prime ministers of northern European countries and Spain, were set to attend events dedicated to the anniversary and discuss supporting Ukraine with President Volodymyr Zelenskiy amid a recent US policy shift under President Donald Trump.
In the latest sign of Europe's efforts to rework its strategy on Ukraine to respond to Trump's actions, Costa on Sunday announced he would convene an emergency summit of the 27 EU leaders in Brussels on March 6, with Ukraine at the top of the agenda.
"We are living a defining moment for Ukraine and European security," Costa said in a post on social media.
The three-year mark of the war in Ukraine came at a sensitive moment for Kyiv as Zelenskiy navigates a rapidly changing international environment upended by changes to US policy by Trump.
The US leader has sought to follow through on his campaign promises to end the war quickly, though his methods for doing so have alarmed many in Ukraine and Europe who believe his approach is too conciliatory toward Russia and its president, Vladimir Putin.
Russia's foreign ministry said on Saturday that preparations for a face-to-face meeting between Trump and Putin were under way, and US officials have acknowledged they had agreed with Moscow to re-establish diplomatic ties and restart economic co-operation.
And on Sunday, Russian Deputy Foreign Minister Sergei Ryabkov told the state TASS news agency that Moscow and Washington would continue bilateral talks at the end of next week, adding that "quite a lot" of contact was ongoing between the Russian and American sides.
Leaders across the EU, fearing both that Trump's approach to Ukraine would lead to an unfavourable settlement for Kyiv and that they - some of Ukraine's most important supporters - would be sidelined in negotiation for peace, have rushed to assert their own response to the rapidly shifting environment.
The UK was expected to announce new sanctions against Russia on Monday, having earlier described them as the biggest package since the early days of the war.
Foreign Secretary David Lammy on Sunday said the measures would be aimed at eroding Russia's "military machine and reducing revenues fuelling the fires of destruction in Ukraine".
British Prime Minister Keir Starmer and French President Emmanuel Macron were to both visit Washington this week as Europe attempts to persuade Trump not to abandon Ukraine in pursuit of a peace deal.
Meanwhile, Ukrainian air defences downed 113 drones launched by Russia at 12 regions overnight with another 71 "lost", according to the daily air force report.
The report said that as a result of the attack, Dnipropetrovsk, Odessa, Kyiv, and Khmelnytskyi regions "suffered", but did not provide further details.
On Sunday, the eve of the war's three-year anniversary, Zelenskiy said Russia had launched 267 drones into Ukraine overnight, more than in any other single attack of the war.
With Reuters
