The early polls were called by Prime Minister Yulia Tymoshenko who accused Chernovetsky of corruption.
With the final results to be announced later on Monday, Chernovetsky has so far garnered 37.75%, followed by Oleksandr Turchynov, a candidate from Yulia Tymoshenko's bloc, with 18.46%, and heavyweight boxing champion Vitaly Klitschko, who has 17.61% of votes.
Chernovetsky's bloc is also leading in city hall elections with 25.7% of the vote. Yulia Tymoshenko's bloc has so far collected slightly over 23% of the vote, followed by Klitschko's party with 12%.
The Tymoshenko and Klitschko blocs are currently in talks to create a possible alliance in opposition to Chernovetsky and his party's city hall majority.
In the previous mayoral elections, Klitschko lost to Chernovetsky. In his latest election campaign the athlete pledged to fight corruption and lead the country out of chaos.
The election could result in a new power struggle between Tymoshenko and President Viktor Yushchenko. Interior Minister Yuriy Lutsenko was cited in a respected Russian daily on Monday as saying that the president's circle was planning to dismiss the government later this week.
There were 70 candidates in the mayoral race. The main candidates have already filed legal complaints against each other for violations during Sunday's voting, Kommersant said.
The Kiev election commission said voter turnout was higher than 50%.
