The exit polls give President Petro Poroshenko's bloc almost a quarter of the vote.
But there's still a chance he'll be forced into a coalition with the People's Front, led by Prime Minister Arseniy Yatsenyuk.
The results, if confirmed, tilt the former Soviet republic towards Europe and away from Russia.
Ukraine's President, Petro Poroshenko, called the snap poll a bid to set Ukraine on a new path after the ousting of pro-Russian leaders.
Mr Poreshenko says the results show people support his pro-Western course and his search for what he calls "political methods" to end the war in the country's east.
"It is reassuring that the majority have voted for the political forces that support the president's peace plan and look for political solutions to the situation in Donbass, paying attention to strengthening of our armed force."
The election was boycotted by pro-Russian rebels in the east, who plan to hold their own polls next month, even though they are unlikely to be recognised by any government in Kiev.
Voters in Crimea and in separatist-controlled areas of the eastern Lugansk and Donetsk provinces were unable to cast ballots - ruling out about five million of Ukraine's 36.5 million-strong electorate.
Twenty-seven seats in the 450-seat parliament will remain empty.
Leader of the Poroshenko bloc, Yuriy Lutsenko, has welcomed the voting trend.
"Our assessment of this election is like this: we are happy that we see the ratings of this election which demonstrate the European and sovereign choice of the Ukrainian nation."
A street revolt eight months ago toppled Ukraine's former pro-Russian president, Viktor Yanukovych.
The mayor of Kiev, Vitaly Klitschko, says the poll shows Ukrainians are united for change.
"We have shown with our own example that we can unite for European values. We need to unite as we have external challenges and we have internal challenges. We need to unite further. All democratic forces should unite steadily because we face great challenges."
The parties now face the major challenge of uniting Ukraine.
Although most parties are pro-Western, they remain divided on key issues - such how to enact reform, battle corruption or fight the war in the east.
The poll comes at a time of deepening economic gloom for Ukraine, with predictions that Gross Domestic Product will fall between seven and ten per cent this year.
Meanwhile, fighting continues despite a shaky ceasefire between government troops and pro-Russian rebels.
War-weary residents say they just want peace.
"More than anything we want peace. The most important thing is good peace, so everything will be calm and peaceful, so they will not be shooting at our grandchildren."
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