German Chancellor Olaf Scholz, French President Emmanuel Macron and Italian Prime Minister Mario Draghi were due to arrive in Kyiv on Thursday, the French presidential palace said.
Scholz, Macron and Draghi took an overnight train to Kyiv from Poland, the French AFP news agency reported.
They are expected to meet with Ukrainian President Volodymyr Zelenskyy.
Major German and Italian media outlets, including Germany's ZDF and Italy's Repubblica, had earlier published a photo of the three leaders on the train.
It is the first time the three travel to Kyiv since the war started in Ukraine.
There has been speculation earlier this week that Scholz would be part of the joint trip ahead of a G7 summit at the end of June.
The visit, seen as a symbol of European unity in support of Ukraine, also comes a day before the European Commission is set to make a recommendation on Ukraine's status as an EU candidate.
The three leaders have come under criticism over their response to the war. Critics say France and Germany, and, to a lesser extent, Italy, have been slow to deliver weapons to Ukraine. Scholz and Macron have also been criticized for maintaining contact with Russian President Vladimir Putin, DW reports.
