Ukrainian comedian Volodymyr Zelensky is set to become the country's next president.
With 42 per cent of ballots counted, exit polls showed that the political newcomer has won the run-off election by a landslide with more than 70 per cent support.
His rival, incumbent president Petro Poroshenko, has admitted defeat but told supporters he will not leave politics.
"I will never let you down," Zelensky told his supporters, adding, "I'm not yet officially the president. But as a citizen of Ukraine, I can say to all countries in the post-Soviet Union: Look at us. Anything is possible!"

Trump says Iran war deal close as Strait of Hormuz tensions linger
Two killed, 10 injured in Ukraine attack on Russia's border Bryansk region
Trump cancels US strikes on Iran, citing progress in talks
South Korea court sentences ex-President Yoon to 30-year jail term in drone case
Thai king's eldest daughter dies, aged 47, after long illness
