Ukraine, an aspiring EU member, described the talks as a “historic event” and the first such meeting “within the future borders of the European Union”.
But they took place following an election result in Slovakia that could put a Russia-friendly government in power, as well as horse-trading in Washington that saw aid for Ukraine struck from the US budget.
The developments come with Ukraine making only gradual advances in a counter-offensive to retake territory from Russia, raising fears of war fatigue among its allies.
Seeking to hold the line, the EU's top diplomat Josep Borrell said on Monday that ministers had come to Kyiv “with a will to express their commitment”.
“This war is having deep consequences for the whole world, but for us Europeans. it’s an existential threat. Maybe it’s not being seen like this for everybody around the world,” he said.
The talks were expected to touch on possible future peace talks after a meeting in Saudi Arabia in August that Ukraine described as productive.
Ukraine's Foreign Minister Dmytro Kuleba played down the cracks in the western alliance, calling the US budget row “an incident” that did not suggest “the US support has been shattered”.
President Joe Biden's Democrats accepted a budget deal that removed assistance for Ukraine to stop Republicans in Congress from shutting down the government. The standoff comes with a US election on the horizon that could return Donald Trump to power.
“Against the background of a potential shutdown in the United States, the decision was taken as it was. We are now working with both sides of the Congress to make sure that it does not repeat again under any circumstances,” Mr Kuleba said.
Denmark's Foreign Minister Lars Lokke Rasmussen said he took “great relief” from Mr Biden's assurances that he would push for continued US aid to Ukraine.
He said Europe “should be ready to do even more” to support Ukraine and “send a strong transatlantic signal, that’s what going on our own soil is something we have to take on a great responsibility for”.
Ukraine-Russia conflict – in pictures
Latvian representative Andris Pelss sought to play down divisions hanging over the meeting, saying “the fact that we are all here also shows how wide and deep the support is”. Croatia's foreign minister Gordan Grlic Radman said the visit “sends a message of how united we are”.
After Slovakia's newly crowned election winner Robert Fico said the country had “bigger problems” than the war in Ukraine, Mr Kuleba said it was too early to judge the impact.
Ukraine “respects the choice the people of Slovakia made,” he said, with Mr Fico set to begin coalition talks on forming a new government.
The result in Slovakia was celebrated by Hungary's nationalist government, which has been the main dissenting voice on EU sanctions on Russia.
Poland's once-steadfast support for Ukraine has also been called into question by a row over agricultural exports, while a Russia-friendly far-right party is enjoying rising popularity in Germany.
Any Ukrainian membership of the EU will eventually have to be backed by all the bloc's current members.