Speaking in a televised interview alongside his wife Olena to mark the third anniversary of his inauguration, Mr Zelensky said the war could only end at the negotiating table.
“The victory will be difficult, it will be bloody and in battle, but its end will be in diplomacy. I am very convinced of this,” he said.
“There are things that we can’t bring to an end without sitting at the negotiation table. That’s how it is because we would like to get everything back, and Russia doesn’t want to give back anything.”
The last diplomatic talks between the two sides took place on April 22, according to Russian state media.
Mr Zelensky said his forces had “broken the backbone” of the Russian army but would have to “finish” the conflict through diplomatic means.
He vowed that the Ukrainian defenders of the besieged Azovstal steelworks in Mariupol would be rescued after Moscow claimed that they had surrendered earlier this week.
“We will bring them home,” Mr Zelensky said of the fighters captured by Vladimir Putin’s forces.
Russia’s defence ministry on Friday announced that its troops had removed the last remaining fighters from the plant’s miles of underground tunnels, ending the bloodiest siege of the war.
Mr Zelensky added that a number of pilots had died “heroically” while trying to fly medication, food and water into the plant and evacuate wounded soldiers.
His comments came amid rising concern over the fate of the soldiers at Azovstal after a Russian official suggested they could face a tribunal for their wartime actions.
The Kremlin has claimed that the captured soldiers will be treated “in line with international laws”, though the chairman of the State Duma, Vyacheslav Volodin, on Tuesday branded them as “Nazi criminals” – stoking fears they could face a trial or the death penalty.
Denis Pushilin, the head of an area of eastern Ukraine controlled by Moscow-backed separatists, said on Saturday that a tribunal for the fighters was “inevitable”.
“I believe that justice must be restored. There is a request for this from ordinary people, society, and, probably, the sane part of the world community,” Russian state news agency Tass quoted Mr Pushilin as saying.
Ukraine’s military this week told the fighters holed up in the plant, hundreds of them wounded, that their mission was complete and they could come out. It described their extraction as an evacuation, not a mass surrender.