Ukraine's Volodymr Zelensky says he has had a "long and meaningful" phone call with China's Xi Jinping, their first contact since Russia's war began.
He said on Twitter he believed the call, along with the appointment of an ambassador to Beijing, would "give a powerful impetus to the development of our bilateral relations".
China confirmed the call, adding that it "always stood on the side of peace".
Unlike the West, Beijing has sought to appear neutral on the Russian invasion.
But it has never hidden its close ties to Moscow, or condemned the invasion, and last month President Xi paid a two-day state visit to Russia.
He referred to President Vladimir Putin as his "dear friend", proposed a vague 12-point peace plan and insisted that China stood on the right side of history.
However, he made no commitment to providing Russia with weapons.
Within days of the visit, President Zelensky invited the Chinese leader to visit Kyiv for talks, noting they had contact before the full-scale war but nothing since it began in February 2022.
In a readout of Wednesday's phone call, China quoted President Xi as saying that China, "as a responsible majority country", would "neither watch the fire from the other side, nor add fuel to the fire, let alone take advantage of the crisis to profit".
That statement appeared to be a swipe at China's biggest international rival, the US, which has provided the most help towards Ukraine's response to the Russian war.
White House spokesman John Kirby welcomed the phone call as "a good thing" but said it was too early to know whether it would lead to "some sort of meaningful peace movement, or plan or proposal".
The likelihood of China helping to end the war appears remote, not just because Russia has shown no readiness to withdraw its forces from Ukraine's sovereign territory. It is a key demand from Kyiv that President Zelensky reiterated: "There can be no peace at the expense of territorial compromises."
Critics have also questioned the idea of Beijing acting as a mediator, citing not only Mr Xi's firm friendship with Russia's leader but also China's soaring trade with Russia and its refusal even to speak of an "invasion".
Russian foreign ministry spokeswoman Maria Zakharova said Moscow saw "broad concord" with China's approach but said the main barrier was Kyiv's "unrealistic demands". Moscow's own demands include recognition of its annexation of swathes of Ukrainian territory, including Crimea, which was invaded in 2014.
China's 12-point plan to end the war has been widely criticised by Ukraine and the West. It fails to offer clear plans for Ukraine's future security or for territory seized by Russia and includes a proposal for unilateral sanctions to be dropped.
And yet Wednesday's hour-long call did not come as a complete surprise.
Earlier this month, European Commission chief Ursula von der Leyen said that Mr Xi had spoken of his willingness to talk to Ukraine's leader when the "conditions and time are right". She had joined French President Emmanuel Macron on a visit to Beijing.
President Zelensky has repeatedly reached out to the Chinese president, an acknowledgement that China's vast wealth and global influence could swing the outcome of the war.
In its readout of the call, Beijing announced its willingness to engage directly with Ukraine, by sending a special representative on Eurasian affairs to Kyiv and other capitals for "in-depth communication" on a political settlement.
For his part, Mr Zelensky appointed a former minister, Pavlo Ryabikin, as ambassador to Beijing.
Xi Jinping has had recent diplomatic success by persuading Iran and Saudi Arabia to restore ties. While it is possible he may have developed a taste for the role of a key international stakeholder, there may also be an economic element to his intervention.
China's flagging economy is still fragile after years of tight Covid-19 restrictions. It is dependent on export trade and cannot fully bounce back as the war in Ukraine drags on.
News of the phone-call made headline news in China's carefully controlled state media outlets, which printed China's interpretation of the call.
On Chinese social media sites, users appeared supportive, with many calling for peaceful dialogue and supporting what they saw as China acting like a responsible country.
"China must break the deadlock and melt the ice!" read one typical comment.