While the president's powers are limited, the head of state -- who also acts as supreme commander of Finland's armed forces -- helps direct foreign policy in collaboration with the government, meaning the changing geopolitical landscape in Europe will be the main concern for the winner.
Two top politicians lead the pack of nine candidates: former conservative prime minister Alexander Stubb and ex-foreign minister Pekka Haavisto of the Green Party, who is running as an independent.
Polls closed at 8:00 pm (1800 GMT) and public broadcaster Yle then published results of votes cast in advance, which showed Stubb in front with 28.3 percent followed by Haavisto with 25.8 percent.
Almost half, 44.5 percent, of eligible voters had cast their ballot in advance. "Every vote is a relief and the fact that we've got that many votes at the start feels really good... I've never felt this grateful before," Stubb told Yle.
Trailing the frontrunners was far-right Finns Party candidate Jussi Halla-aho at 16.1 percent, who experts believed could potentially make it to the runoff second round.
Hallo-aho told Yle he believed his "share of the vote will improve as the counting of the election day votes progresses." Voter Hannu Kuusitie told AFP the country needs a president with "leadership" and "humanity".
"Of course, he must also be tough when necessary," he added.Relations between Moscow and Helsinki deteriorated following Russia's 2022 invasion of Ukraine, prompting Finland to drop decades of military non-alignment and join NATO in April 2023.
Russia, with which Finland shares a 1,340-kilometre (830-mile) border, swiftly warned of "countermeasures".
Humans as weapons
By August 2023, Finland observed an influx of migrants entering through its eastern border without visas. Helsinki claimed Moscow was pushing the migrants in a hybrid attack to destabilise it, and Finland closed the eastern border in November.
"We are in a situation now where Russia and especially Vladimir Putin is using humans as a weapon," Stubb said on Thursday evening during a final televised debate.
"It's a migrant issue, it's a ruthless, cynical measure. And in that case we have to put Finland's security first," he added. Main rival Haavisto stressed that Finland had to "send Russia a very clear message that this can't go on".
In the post-Cold War period, Helsinki maintained good relations with Moscow.
Incumbent President Sauli Niinisto -- who is stepping down after serving two six-year terms -- once prided himself on his close ties with Russian President Vladimir Putin before becoming one of his most trenchant critics.
Against this backdrop, all the presidential candidates are championing both Finland's independence and its new role as a NATO member, said Hanna Wass, vice dean at the Faculty of Social Science at the University of Helsinki.
"They all seem to have a strong idea emphasising self-sufficiency," Wass told AFP, adding that the candidates believe that Finaldn should "also be an active contributor in building a shared European defence and Nordic cooperation."
With such similar stances, the election will focus more on the candidates' personalities, according to Tuomas Forsberg, professor of foreign policy at the University of Tampere.
"This will be more about electing an individual, where you look at the person's credibility and reliability and perceived qualities as a leader of foreign policy," Forsberg said.
Similar views
Stubb was prime minister of Finland between 2014 and 2015, while Haavisto has held several ministerial posts. "They both have broad experience in both domestic and foreign politics, which voters seem to value the most," Wass said.
While sharing similar political views, Haavisto and Stubb represent different backgrounds, Forsberg noted. "Alex is more a representative of the right and Haavisto of the left, even if... he has taken the middle road as a Green," Forsberg said.
In a second voting round between the two -- which will be held on February 11 unless a candidate receives more than 50 percent -- the election debates could be decisive, he added.