Ukrainian comedian Volodymyr Zelensky scored a landslide victory in the country's presidential election.

With nearly all ballots counted in the run-off vote, Mr Zelensky had taken more than 73% with incumbent Petro Poroshenko trailing far behind on 24%.

"I will never let you down," Mr Zelensky told celebrating supporters.

Ukrainian comedian and presidential candidate Volodymyr Zelensky kisses his wife Olena after the announcement of the first exit poll results in the second round of Ukraine's presidential election at his campaign headquarters in Kiev on April 21, 2019. PHOTO | AFP

Russia says it wants him to show "sound judgement", "honesty" and "pragmatism" so that relations can improve. Russia backs separatists in eastern Ukraine.

The comments came from Russian Prime Minister Dmitry Medvedev, in a Facebook post on Monday (in Russian).

He said he expected Mr Zelensky to "repeat familiar ideological formulas" that he used in the election campaign, adding: "I have no illusions on that score.

"At the same time, there is a chance to improve relations with our country."

Outgoing Ukrainian President Petro Poroshenko (right) raises his hand with his wife Maryna at his party headquarters in Kiev on April 21, 2019, at the end of a day of polling in the second round of national elections in which he lost to comedian Volodymyr Zelensky. PHOTO | AFP

Mr Poroshenko, who admitted defeat after the first exit polls were published, has said he will not be leaving politics.

He told voters that Mr Zelensky, 41, was too inexperienced to stand up to Russia effectively.

Billionaire Poroshenko, who has been in power since 2014, was elected after an uprising overthrew the country's previous pro-Russian government.

Mr Zelensky, a political novice, is best known for starring in a satirical television series “Servant of the People”, in which his character accidentally becomes Ukrainian president.

Ukrainian comedian and presidential candidate Volodymyr Zelensky speaks to the media during press conference at his campaign headquarters in Kiev on April 21, 2019, after the announcement of the first exit poll results in the second round of Ukraine's presidential election, that showed him as the winner. PHOTO | AFP

He told reporters he would "reboot" peace talks with the separatists fighting Ukrainian forces and volunteers in the east.

"I think that we will have personnel changes. In any case we will continue in the direction of the Minsk [peace] talks and head towards concluding a ceasefire," he said.

There are sporadic skirmishes and the situation also remains tense around Crimea, annexed from Ukraine by Russia in 2014.