Recent opinion polls gave Dalia Grybauskaite a big lead over her closest rivals: lawmaker Arturas Paulauskas and European Parliament member Zigmantas Balcytis.
Dalia Grybauskaite, 58, is hoping to secure more than 50% of the votes to avoid a run-off.
The election comes amid rising security concerns in the region after Russia’s annexation of Crimea from Ukraine.
Polling stations across the Baltic state will open at 04:00 GMT and will close at 17:00 GMT.
Some 2.5 million people are eligible to cast their ballots.
With Dalia Grybauskaite seen by many as a hot favorite, critics say the campaigning lacked energy.
“I have never seen in any country such a dull election campaign,” former President Valdas Adamkus was quoted as saying by the Associated Press news agency.
First results are expected shortly after the voting ends.
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