Ukrainian comedian Volodymyr Zelensky has won a run-off election to become the country's next president by a landslide, exit polls suggest.
The polls give him more than 70 per cent support. He dominated the first round of voting three weeks ago when 39 candidates were on the ticket.
Mr Zelensky challenged incumbent president Petro Poroshenko.
Mr Poroshenko has admitted defeat but told supporters gathered in Kiev that he will not leave politics.
Ukraine's president holds significant powers over the security, defence and foreign policy of the country.
"I will never let you down," Mr Zelensky told his supporters on Sunday.
He added: "While I am not formally president yet, as a citizen of Ukraine I can tell all post-Soviet countries: 'Look at us! Everything is possible!'"
If polls are correct, he will be elected for a five-year term.
Polls gave Mr Poroshenko, who has been in power since 2014, 25 per cent of the vote.
The billionaire was elected after an uprising overthrew the country's previous, pro-Russian government.
Mr Zelensky, 41, is best known for starring in a political satirical drama in which his character accidentally becomes Ukrainian president.
With no previous political experience, his campaign focused on his difference to other candidates rather than on any concrete policy ideas.