Polls opened at 7 a.m. (01:30 GMT) at over 13,000 polling stations and closed at 4 p.m., after which vote counting began. Of Sri Lanka's 22 million population, approximately 17 million were eligible to vote.
The initial results are expected before midnight, with the final tally is due to be announced on Sunday, Commissioner General of Elections Saman Sri Ratnayake said.
If no candidate secures 50% of first-choice votes, the top two candidates will go into the second round of counting that will also include ballots featuring them as a second preference.
Interim President Ranil Wickremesinghe, who took office after President Gotabaya Rajapaksa fled the country in July 2022 amid economic and political turmoil, is seeking reelection. He is being challenged by 38 candidates. The frontrunners are Anura Kumara Dissanayake, of the left-wing JVP, and opposition leader Sajith Premadasa.