The woman had made it up to the 24th floor before being stopped Friday night, police said.
Building security found the 31-year-old roaming a hallway around 9:30 p.m., said police.
It is believed the woman entered through the tenants' entrance in the building's lobby, which is open to the public, said police.
The woman told officers she was there to visit her uncle but it’s not yet known if she had any relatives in the building, police said.
She was not violent and did not pose a threat to President-elect Donald Trump, who keeps his offices on the top floors of the 58-story building, police said.
The woman was taken to New York Presbyterian-Weill Cornell Medical Center for evaluation and has not been charged with a crime, police said.
Security at Trump Tower has recently come under scrutiny by officials who estimate it costs the city $1 million a day.