At the same time, he said Ukraine would not allow Russian forces to regroup after their withdrawal from Kherson, and said there would be more fighting until Ukraine reclaims control of all of its occupied territory.
Zelenskiy made his remarks in a speech to a Group of 20 (G20) summit in Indonesia, where Russia's invasion of Ukraine was a key focus of discussion among leaders of the world's major economies.
A day earlier he shook hands with soldiers and waved to civilians during a visit to Kherson, where he said Ukraine had gathered evidence of at least 400 war crimes committed by Russian troops including killings and abductions.
"I am convinced now is the time when the Russian destructive war must and can be stopped," he said via video link to the summit on the island of Bali, according to a copy of his speech reviewed by Reuters.
Zelenskiy told the summit that now was the time to stop Russia's war in his country under a plan he has proposed "justly and on the basis of the UN Charter and international law".
He called for restoring "radiation safety" with regard to the Zaporizhzhia nuclear power plant, and proposed that "International Atomic Energy Agency (IAEA) missions are sent to all Ukrainian nuclear plants".
Russian Foreign Minister Sergei Lavrov, who headed the Russian delegation to the summit, remained in the room while Zelenskiy was speaking, delegates said.
British Prime Minister Rishi Sunak said that the G20 saw international condemnation of Russia's war in Ukraine.
"With Russia's Foreign minister sitting there we highlighted both the illegality and the barbaric nature of Russia's war and also the devastating impact that it is having on people around the world through higher food and energy prices," Sunak said.
Sunak arrived at the summit in Bali, Indonesia, on Monday (November 14) and is expected to meet Russian Foreign Minister Sergei Lavrov.
The British PM on Tuesday extended his support for Ukraine at the G20 summit while confirming a long-planned order for warships from British defence contractor BAE Systems.