President Volodymyr Zelensky is set to become the first Ukrainian leader since the fall of communism to command an overall majority in parliament.
‘Servant of the People,’ the party named after the TV sitcom that made him famous, has won 43.1% of the vote with almost 94% of results counted.
The party is on course to win 253 of parliament’s 450 seats.
A decisive win for Mr Zelensky’s party will make it easier for him to push through reforms and tackle corruption.
It will also be the best result by any party in Ukraine’s post-1991 history.
Since he triumphed in April’s presidential poll, Mr Zelensky, 41, has been unable to appoint the ministers he wants.
On Sunday, 424 seats in the parliament, the Verkhovna Rada, were contested. Those seats not included represent the war-torn Donbas region and Crimea, which was annexed from Ukraine by Russia in 2014.