Duda, whose term in office expires in 2025, was one of Trump's preferred international partners during his 2017-2021 presidency and they have described themselves as friends.
In contrast, many other European leaders have long been nervous that a second Trump presidency would mean decreased U.S. support for Poland's eastern neighbour Ukraine and for the NATO military alliance.
"The people of Poland love him (Duda)... and that's not an easy thing to accomplish, but he's done a fantastic job and he's my friend," Trump told reporters as Duda arrived at Trump Tower.
"We're behind Poland all the way," he added.
The Trump campaign said in a readout of the meeting that they had discussed a proposal from Duda that NATO members spend at least 3% of their gross domestic product (GDP) on defence. The current minimum target is 2%.
"They also discussed the war between Russia and Ukraine, the conflict with Israel in the Middle East, and many other topics having to do with getting to world peace," the campaign said.
After their dinner Duda said it was "a friendly meeting in a very nice atmosphere".
Trump, who is on trial in New York over accusations that he covered up a "hush money" payment to pornographic actress Stormy Daniels, is likely to face a tight race against President Joe Biden, a Democrat, in the November presidential election.
Duda is in New York to attend the United Nations, and will travel on to Canada on Friday.
(Reporting by Alan Charlish in Warsaw, additional reporting by Nathan Layne; Editing by Gareth Jones)
