Ammon News - The talks are scheduled for 10:00 local time (08:00 BST) in Istanbul's Dolmabahce Palace and will be closed to the press, Russian news agency TASS reported, citing a source familiar with the matter.
Zelensky will be in the Turkish capital Ankara on Thursday to meet President Recep Tayyip Erdogan.
He said he would attend direct talks in Istanbul with Russia, but only if Putin also attended.
"I am waiting to see who will come from Russia, and then I will decide which steps Ukraine should take. So far, the signals from them in the media are unconvincing," he said in his nightly video address on Wednesday.
Putin and Zelensky have not met in person since December 2019. Russia and Ukraine last held direct negotiations in March 2022 in Istanbul, shortly after Moscow launched its full-scale invasion of its neighbour.
Fighting has raged in Ukraine since then. Russian forces have slowly expanded the amount of territory they control over the past year, mostly in the east of Ukraine.
On Sunday Putin called for direct talks between Russia and Ukraine in Turkey's largest city "without pre-conditions". Zelensky then announced he would go in person and expected the Russian president to travel as well.
Putin's suggestion of direct talks in Istanbul followed Western powers' call for a 30-day ceasefire, after European leaders met in Kyiv on Saturday.
After Trump called for Ukraine to accept the offer on Sunday, Zelensky said he would travel there himself.
"There is no point in prolonging the killings. And I will be waiting for Putin in Türkiye on Thursday. Personally," Zelensky wrote in a social media post.
Earlier on Wednesday, Trump had floated the possibility of joining the meeting himself if Putin did.
The US president, who is currently in Qatar, told reporters he did not know if his Russian counterpart would attend "if I'm not there". BBC