The summit on Saturday will discuss a US and European proposal for a 30-day ceasefire in the Russian war in Ukraine that if refused by Moscow would see them impose new sanctions, a French diplomatic source said, adding that the step had not been finalised.
The visit by British Prime Minister Keir Starmer, French President Emmanuel Macron, German Chancellor Friedrich Merz and Polish Prime Minister Donald Tusk is the first time the leaders have travelled together to Ukraine.
"Alongside the US, we call on Russia to agree a full and unconditional 30-day ceasefire to create the space for talks on a just and lasting peace," the four leaders said in a joint statement.
Zelenskiy accompanied them as they paid their respects at a memorial to honour Ukrainian soldiers killed in the war.
The visit comes at an unpredictable diplomatic moment in Russia's more than three-year-long war against Ukraine.
US President Donald Trump is pushing for a rapid peace after tearing up the policies of his predecessor since entering the White House in January.
After engaging with Russian officials, clashing publicly with Zelenskiy and briefly cutting vital military aid to Ukraine, the Trump administration has patched up ties with Kyiv and signed a mineral resources deal.
Trump has also shifted his tone, signalling growing frustration with what Washington views as Putin's foot-dragging over a ceasefire.
Trump has threatened to step up sanctions against Russia, but he has also said he could abandon the peace effort if there is no breakthrough.
He called on Thursday for a 30-day ceasefire and Zelenskiy said he would be ready to implement it immediately.
The European Union has joined the call for a 30-day ceasefire.
Kremlin spokesman Dmitry Peskov suggested that Western military assistance for Ukraine would have to stop in order for a temporary ceasefire to happen.
"Otherwise it will be an advantage for Ukraine," he said.
Western military aid has been vital for Ukraine since Russia's full-scale invasion in February 2022.
Putin hosted Chinese President Xi Jinping and other leaders at a Red Square military parade on Friday to mark the 80th anniversary of the Soviet Union's victory over Nazi Germany in World War II, sending a defiant message that he is not isolated.
On the same day, European ministers voiced support for a special tribunal to prosecute the Russian president and his officials for crimes of aggression, showing support for Zelenskiy who poured scorn on Putin for planning a "parade of bile and lies".
On the eve of the summit, the US embassy in Kyiv warned of a "potentially significant" air attack in the coming days.
"There is a lot of work to do, a lot of topics to discuss," said Andriy Yermak, Zelenskiy's chief of staff, posting photographs welcoming the leaders after their train pulled into Kyiv.
"We must end this war with a just peace. We must force Moscow to agree to a ceasefire."
The leaders are expected to host a virtual meeting with other leaders to update them on progress being made for a future coalition of an air, land and maritime force that would help regenerate Ukraine's armed forces after any peace deal.
The visit falls on the final day of a May 8-10 ceasefire declared by Putin that Ukraine did not accept, denouncing it as a sham.
Both sides have accused each other of violating it.
