A comedian with no political experience has won a landslide victory as the next president of Ukraine.

Incumbent Ukrainian President Petro Poroshenko conceded he has been soundly defeated in a run-off vote by comedian Volodymyr Zelenskiy and would be leaving office next month, but says he does not plan to quit politics altogether.

Ukraine entered uncharted political waters on Sunday after an exit poll showed Zelenskiy, a comedian with few detailed policies, had easily won enough votes to become the next president of a country at war.

The election of Volodymyr Zelenskiy, 41, is a bitter blow for incumbent Poroshenko who tried to rally Ukrainians around the flag by casting himself as a bulwark against Russian aggression and a champion of Ukrainian identity.

The national exit poll on Sunday showed Zelenskiy had won 73 per cent of the vote with Poroshenko winning just 25 per cent.

Zelenskiy, who plays a fictitious president in a popular TV series, will now take over the leadership of a country on the front line of the West’s stand-off with Russia following Moscow’s annexation of Crimea and support for a pro-Russian insurgency in eastern Ukraine.

Zelenskiy’s victory fits a pattern of anti-establishment figures unseating incumbents in Europe and further afield. He has promised to end the war in the eastern Donbass region and to root out corruption amid widespread dismay over rising prices and falling living standards.

But he has been coy about exactly how he plans to achieve all that. Investors want reassurances that he will accelerate reforms needed to attract foreign investment and keep the country in an International Monetary Fund program.

-AAP