- Volodymyr Zelensky, who plays a fictional president in a popular TV show, secured 30.4 percent of the vote on Sunday, early results showed.
- Petro Poroshenko, a billionaire magnate and Ukraine's current leader, received 17.8 percent.
- In a country on the frontline of the West's standoff with Russia, the electorate has rallied behind an anti-establishment figure promising to combat deep-seated corruption.
A comedy actor with no political experience has thrashed the incumbent in the first round of Ukraine's presidential elections, according to exit polls.
Volodymyr Zelensky, who plays a fictional president in a popular TV show, secured 30.4 percent of the vote on Sunday, early results showed. Petro Poroshenko, a billionaire magnate and Ukraine's current leader, received 17.8 percent.
With no-one expected to secure a majority when the final results are confirmed later on Monday, the two largely pro-EU candidates are set to go head-to-head in a run-off vote on April 21.
"If I win, we will (have) a strong democratic Ukraine — without corruption," Zelensky told CNBC's Steve Sedgwick in Kiev on Sunday.
"This is the biggest problem," Zelensky said, when asked whether fighting corruption would be a priority under his leadership.
In a country on the frontline of the West's standoff with Russia, the electorate has rallied behind an anti-establishment figure promising to combat deep-seated corruption.
Zelensky must now convince voters he is fit to lead a country at war and at the center of the West's tussle with Moscow.
Market participants are also likely to closely monitor whether the country's next president will favor reforms needed to keep Ukraine in an International Monetary Fund (IMF) bailout program.
"We will do diplomatic meetings … We don't want war. We don't want to fight, we want to stop the war in Donbass," Zelensky told CNBC.
The presidential elections represent the first national vote since Russia annexed Crimea in early 2014 and subsequently supported an uprising by pro-Russian separatists in east Ukraine.
The armed conflict in the eastern Donbass region has died down following numerous cease-fires that have been implemented and then collapsed. Attempts to stop the conflict were made in Minsk in late 2014 and again in 2015 (known as the Minsk Agreement) but both sides accuse each other of not complying with agreed conditions.
Poroshenko's presidency has been dominated by relations with Russia and he has been closely watched for his responses to instances of Russian aggression toward, or provocations of, Ukraine — such as the incident in the Kerch Strait last November in which three Ukrainian Navy vessels were seized.
The current leader has attempted to portray Zelensky as a candidate unfit to represent Ukraine abroad, especially in taking on Russian President Vladimir Putin in international talks.
But, widespread corruption and frustration over low living standards in one of Europe's poorest countries appears to have fueled Zelensky's rise to prominence.
Ukrainian Foreign Minister Pavlo Klimkin told CNBC on Monday that the first-round election result was a case of "democracy in action."
However, Klimkin stressed it was important for external observers to understand that whoever ended up winning the upcoming run-off vote, Kiev had decisively turned its back on close ties with Moscow.
"It is forever. If you talk to the people on the streets, it is forever," Klimkin said, adding the electorate would simply not allow the next administration to U-turn on this issue.
"Ukraine will continue its drive towards the transatlantic community towards NATO, towards the European Union. There could be some differences in time-frames and tactics but in the sense of strategy, it is decided 100 percent," he said.
"Corruption and the rule of law … Whoever becomes president, they are the number one goals for them because if they don't fulfil these hopes of the population, they will lose quite shortly," Tomas Fiala, CEO of Ukrainian investment bank Dragon Capital, told CNBC Monday.
Fiala said Zelensky's policy pledges had generated the "right headlines" in recent weeks, with the comedian promoting co-operation with the IMF, conservative fiscal policy and privatization.
But, he warned Zelensky was "very fresh" to politics and his knowledge of economics and geopolitics was unlikely to be "deep enough."
Zelensky is accused of being a puppet of controversial oligarch Ihor Kolomoisky who owns the TV channel that Zelensky's comedy shows have appeared on. The oligarch has denied that he financially supports Zelensky.
Poroshenko described the result as a "harsh lesson" and appealed for greater support from younger voters in the second round.
"Poroshenko is a very experienced politician, so he will fight to the bitter end… Zelensky's campaign should never relax," Aivaras Abromavicius, a former Ukrainian economy minister, told CNBC on Sunday.
When asked whether voters would need to see more policy detail from Zelensky ahead of the second round, Abromavicius replied: "Absolutely."
— CNBC's Holly Ellyatt contributed to this report.