Putin on Sunday proposed direct negotiations with Ukraine in Istanbul and Zelenskiy had said he would be waiting for the Kremlin leader.
But after keeping the world guessing for days about Putin's plans, the Kremlin late on Wednesday named a delegation that did not include the president.
It was unclear how Ukraine - which has so far not publicly committed to send anyone to talks in Istanbul or to name a delegation - would respond.
There was confusion in the Turkish city, where reporters were gathered near the Dolmabahce palace offices that the Russians had specified as the talks venue. Turkish officials have given no information on the time or location.
Russia's TASS news agency said talks would start at 10am (5pm AEST) on Thursday, but a Ukrainian official dismissed that, saying there had been no agreement on when they might begin.
Zelenskiy, who is due to meet Turkish President Recep Tayyip Erdogan in Ankara on Thursday, had said earlier this week he was not prepared to talk to anyone on the Russian side except Putin, and goaded the Kremlin leader by questioning if he was brave enough to show up.
The Kremlin says Putin - who is also under threat of an additional tightening of European sanctions to "suffocate" Russia's economy - does not respond to ultimatums.
The two sides last held face-to-face talks - also in Istanbul - in March 2022, only weeks after Putin sent his army into Ukraine.
Both are trying to show US President Donald Trump they are serious about peace, as he presses them to end what he calls "this stupid war".
Washington has threatened repeatedly to abandon its diplomatic efforts to settle the conflict unless there is clear progress.
After leaning heavily on Ukraine and clashing with Zelenskiy at a meeting in the Oval Office in February, Trump has shown increasing impatience with Putin in recent weeks and threatened additional sanctions to hit Russian trade.
Trump, who is on a three-nation tour of the Middle East, said on Thursday he would go to the talks in Turkey on Friday "if it is appropriate".
The confirmed absence of Putin lowers the expectations for a major breakthrough in the conflict, the deadliest in Europe since World War II.
Zelenskiy backs an immediate 30-day ceasefire, but Putin has said he first wants to start talks at which the details of such a truce could be discussed.
US Secretary of State Marco Rubio, speaking at a NATO meeting in Turkey, said there was no military solution to the conflict, and Trump was open to "virtually any mechanism" that would lead to peace.
The Russian delegation named by the Kremlin is headed by presidential adviser Vladimir Medinsky and includes a deputy defence minister, a deputy foreign minister and the head of the GRU military intelligence agency.
The Kremlin said Putin had held a late-night meeting with ministers, military commanders and spy chiefs to discuss the upcoming talks.
Estonia, an EU and NATO member that strongly backs Ukraine, said Putin was delivering a "slap in the face" by sending a low-level team.
With Russian forces in control of close to a fifth of Ukraine, Putin has held fast to his longstanding demands for Kyiv to cede territory, abandon its NATO membership ambitions and become a neutral country.
Ukraine rejects these terms as tantamount to capitulation, and is seeking guarantees of its future security from world powers, especially the United States.
