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% support. He dominated the first round of voting three weeks ago when 39 candidates were on the ticket.
"I will never let you down," Mr Zelensky told 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!'"
Incumbent President Petro Poroshenko admitted the defeat but told supporters in Kiev that he will not leave politics.