With the charismatic opposition leader, former Premier Yulia Tymoshenko in jail, the opposition split, and regular Ukrainians disillusioned with politics, Yanukovych's Party of Regions was expected to retain control over parliament despite his rollback on democracy.
The West is paying close attention to the conduct of the vote in the strategic ex-Soviet state, which lies between Russia and the European Union, and serves as a key conduit for transit of Russian energy supplies to many EU countries.
Ukraine's relations with the West have soured over Tymoshenko's jailing, which prompted the EU to freeze a long-awaited partnership deal with Kiev. An election deemed unfair would likely turn Ukraine further away from the West and toward Moscow.
Tymoshenko's top aide, Oleksandr Turchynov, accused authorities of attempting to rig the vote by registering several hundred thousand Ukrainians as ill and voting at home, where any violations are harder to observe.
Another pro-Western party led by world boxing champion Vitali Klitschko said one of its candidates, Olha Herasimyuk, was attacked while she was trying to record an allege vote-buying scheme. Several polling stations in the Black Sea city of Odessa briefly interrupted their work after election officials found pens with disappearing ink in voting booths.
Opposition forces hope to garner enough parliament seats to weaken Yanukovych's power and undo the damage they say he has done: the jailing of Tymoshenko and her top allies, the concentration of power in the hands of the president, the snubbing of the Ukrainian language in favor of Russian, waning media freedoms, a deteriorating business climate and growing corruption.
But the failure of Tymoshenko's and Klitshchko's parties to form a genuine alliance has played into the hands of Yanukovych, and their ability to work together in parliament remains to be seen.
Dmitry Kovalenko, a 50-year-old entrepreneur in Kiev, said he voted for Tymoshenko's Fatherland party in hope of ending Yanukovych's monopoly on power.
"I am against repression," Kovalenko said after casting his ballot at a polling station in central Kiev. "It's easy to win when your opponents are in jail."
While Tymoshenko's and Klitschko's parties are expected to make a strong showing in elections by party lists, half of the 450 seats in the Verkhovna Rada parliament will be allocated to the winners of individual races, in which Yanukovych loyalists are expected to take the lead. Yanukovych has centered his party's campaign on emphasizing stability after years of infighting in the Orange camp and relative economic recovery after the global financial crisis, which hit Ukraine severely.
"Stability, stability, stability is what Ukraine needs," said Olexiy Nalivaichenko, 35, a civil servant in Kiev, who voted for Yanukovych's party. "We want to feel confident and secure about tomorrow."
Also expected to win seats in parliament is the Communist party, which will side with Yanukovych's supporters. Another party that could pass the 5 percent threshold needed for seats is the nationalist Svoboda (Freedom), a staunch government critic infamous for xenophobic and anti-Semitic statements.
The election tainted by Tymoshenko's jailing on charges of abuse of office has also been compromised by the creation of fake opposition parties, campaigns by politically unskilled celebrities, and the use of state resources and greater access to television by Yanukvoych's party.
At one polling station in Kiev, voters complained that a clone politician with the same last name as Fatherland's candidate was intended to split the opposition vote.
"This doesn't look good," said Yevhen Yefimov, 43, a Kiev computer specialist, who was nearly fooled into voting for the fake politician rather than a Tymoshenko candidate. "They are trying to trick people into making a mistake ... to steal Fatherland votes."
* Yuras Karmanau contributed to this report.