Duda, bidding for a second term in office, garnered 51 percent of the vote, according to exit poll projections released in the early hours of Monday.
Meanwhile, opposition-backed challenger Rafał Trzaskowski, the mayor of Warsaw, won 49 percent, the Ipsos survey found.
The polling company said its “late poll” findings combined exit poll data with partial official results and could vary by up to 1 percentage point from the final election returns.
An initial exit poll released on Sunday evening had pointed to a slightly smaller gap between the two runoff contenders, putting Duda's second-round support at 50.4 percent vs. 49.6 percent for Trzaskowski.
The official results of the vote are expected to be announced later on Monday.
Voter turnout was a respectable 67.9 percent, according to the late exit poll.
Poland’s governing conservatives last fall won parliamentary elections for a second consecutive term, and are looking to keep their grip on power by maintaining control of the presidency.
The Polish president has the power to veto legislation passed by parliament, a key prerogative in a country where traditionalists and liberals are bitterly divided.
In a first round of voting in the presidential ballot on June 28, no candidate won an outright majority, meaning a second round had to be held.
Duda won the most votes last month, garnering 43.5 percent. Trzaskowski was runner-up with 30.46 percent, according to the National Electoral Commission (PKW).
‘Long live Poland!’
“Long live Poland!” chanted a jubilant Duda as supporters around him erupted in cheers on election night.
“I promise I won’t disappoint you,” he added, thanking his wife and daughter and the conservative government which backed him in the presidential race.
Andrzej Duda (centre) with his wife (left) and daughter (right). Photo: PAP/Leszek Szymański
Duda said the election campaign had been “brutal,” but called on opponents to show each other respect amid Poland’s bitter political divisions. He invited his challenger to shake hands at the presidential palace.
Trzaskowski did not concede defeat but said he was waiting for the official results to come through.
“We said it would be close and it is close. But I’m absolutely convinced we will win,” he told supporters.
Rafał Trzaskowski with family on election night. Photo: PAP/Radek Pietruszka
Ahead of the vote, conservatives had warned that if Trzaskowski, the candidate of the opposition Civic Platform (PO) party, was elected head of state, he would block a swathe of government initiatives, hampering the administration’s ability to push through core policies.
The Polish presidential election was originally scheduled for May 10, but failed to go ahead amid the COVID-19 pandemic.
Source: Polish Radio/TVP