Nearly 130 heads of state are meeting in New York as the post-World War Two order comes under strain and with the UN itself struggling to remain relevant while weathering attacks from Trump, who has long expressed disdain for the institution and has slashed US funding for many of its agencies.
Trump is expected to arrive in New York on Monday afternoon and will address the UN General Assembly on Tuesday.
"The president will highlight how he has and his administration have confronted complex problems head-on around the world," US ambassador to the United Nations Mike Waltz told reporters.
"He will touch on the importance of ensuring that Iran never has a nuclear weapon."
Hanging over Trump's meetings will be the US-Israeli war with Iran, now more than six months old with no immediate end in sight and at risk of expanding as Yemen's Iran-aligned Houthi militants attack Saudi Arabia and threaten a crucial shipping route.
The conflict with Iran will likely be discussed when Trump participates in a meeting with Gulf Cooperation Council leaders.
He will then hold a reception for the council, during which he is set to have his first in-person meeting with Delcy Rodriguez, the interim president of Venezuela backed by Washington after the US military ousted former Venezuelan President Nicolas Maduro.
Trump is also set to meet on Monday with Democratic Mayor Zohran Mamdani.
The two politicians have criticised each other's policy positions and hold radically different worldviews, yet their first meeting in November at the White House proved to be friendly, and Mamdani described their second meeting earlier this year as productive.
Also on Trump's agenda is Ukrainian President Volodymyr Zelenskiy, who said in a social media post on Sunday he and Trump agreed to meet in New York.
The Ukrainian leader did not say when the meeting would take place, but a person familiar with the matter said it is expected to happen on Tuesday.
On Tuesday, Trump is set for separate bilateral meetings with British Prime Minister Andy Burnham - the first in-person meeting of the two leaders - and with Japanese Prime Minister Sanae Takaichi.
Trump also will meet with Iraqi Prime Minister Ali Faleh al-Zaidi at some point during the UN gathering, Iraqi outlets reported last week.
