"On my way to the United States to strengthen resilience and defense capabilities of Ukraine," Zelensky said on his Twitter account.
"In particular @POTUS and I will discuss cooperation between Ukraine and the United States. I will also have a speech at the Congress and a number of bilateral meetings."
Zelensky is expected to visit the White House and the US Capitol on Wednesday, though security concerns could force a change in plans, two sources familiar with the planning said Tuesday.
Punchbowl News first reported the possible trip, which would be Zelensky's first known visit outside Ukraine since Russia launched its assault on the country on Feb. 24.
Zelensky is expected to meet congressional leadership and national-security committee chiefs from the Republican and Democratic parties and could address a joint session of Congress, Punchbowl reported earlier.
Zelensky made a surprise trip to troops in the battered eastern frontline city of Bakhmut, underlining Russia's stuttering but persistent attempts to capture it. In a Tuesday night video address, he referred to his trip to "Fortress Bakhmut" in Donetsk, one of the provinces Russia claimed in September but most countries reject as illegal occupation.
Zelensky last left Ukraine for the Munich Security Conference on Feb. 19, according to his official schedule. His spokesman did not immediately respond to a written message seeking confirmation.
Earlier on Tuesday, US House of Representatives Speaker Nancy Pelosi said there would be a session of Congress on Wednesday night which would have a "very special focus on democracy."
Pelosi's remarks, which came in a letter, did not elaborate on what the session would be about. Her office did not immediately respond to a request for comment on the reported visit by Zelensky.
US Representative Marcy Kaptur, co-chair of the Congressional Ukraine Caucus, told CBS News there were ongoing efforts to bring Zelensky to the Capitol on Wednesday and to have him address Congress.
"We'd be very honored to have him visit. I'm amazed he can make it in view of the situation. It'd be a great gift to have him at the Capitol. We're working with the leadership to be helpful. We personally understand if he cannot make it last minute," Kaptur was quoted as saying by CBS News.
After President Emmanuel Macron pushed his unpopular pension bill through Parliament without a vote, demonstrations about the changes broke out again.