Prime Minister Donald Tusk, LGBTQ rights and abortion foreign policy have been major issues in the campaign.
Polish voters are voting for the country's next president, which will be a fierce competition between the mayor of Warsaw's Liberal Party and conservative historians.
The polls are open in the election at 7 a.m. local time (5GMT) and the polls are expected to be conducted after the polls are concluded at 9:00 pm (19gmt). The final official outcome of the competition expected on Monday, with 13 candidates set to take place on Monday.
Among the 13 candidates for Sunday's election, the leader is Rafal Trzaskowski, the pro-European mayor of the Polish capital, and Karol Nawrocki, a historian who lost power 18 months ago.
Neither is expected to reach the 50% threshold required for victory, which could be runoff on June 1.
The election is closely watching whether voters agree with the pro-European road set by Prime Minister Donald Tusk or a return to the country's nationalist legal and judicial vision from 2015 to 2023.
Tusk defeated the Legal and Judiciary Party, which has been repeatedly controversial with the EU, and was elected Prime Minister in December 2023.
The executive power of the Polish president is limited, but the commander-in-chief of the armed forces implements foreign policy and can veto legislation.
The movement revolves heavily around foreign policy, with key members of NATO and the EU bordering war-torn Ukraine as security problems in Poland intensified and fears that the U.S. commitment to European security could shake during the Trump era.
Trzaskowski, deputy leader of Tusk’s center-right citizen platform, has promised cement as a major player in Europe’s core role, by contrast to law and justice.
"I will definitely strengthen my relationship with our partners ... within NATO and the EU," Trzaskowski told state broadcaster TVP message on Friday.
Social issues have also been the main theme of the campaign, with Nawrocki using himself as the guardian of conservative values, while Trzaskowski gained support from free voters to declare his commitments to vow abortion and LGBTQ rights.
Malgorzata Mikoszewska, a 41-year-old travel company employee, told AFP that she is a fan of Trzakowski's liberal stance on social issues.
“The most important thing is that I want legal liberalization for abortion and sexual minorities,” she said.
Nawrocki's campaign was boosted when he met with U.S. President Donald Trump at the Oval Office earlier this month.
However, this was hit on his charges, which were for him buying an apartment in Gdansk from an elderly man in exchange for a commitment to provide lifelong care for the undelivered person. Navoloki denied the allegations.
Polish authorities reported attempts to intervene during the campaign, including denial of service attacks against parties to the Tusk-ruling coalition, and allegations from state research institutions that political ads on Facebook were funded from overseas.
"With Nawrocki as president, the government will be paralyzed, which could eventually lead to the downfall of the ruling coalition," political scientist Anna Materska-Sosnowska told AFP.
She said his victory could see a "populists' return" in the next election.
The new president will replace Andrzej Duda, who has served two terms and is not eligible to stand up again. The polling station will be closed at 9 p.m. (18:00 GMT).