Pope Francis said he would attend an international Catholic conference on marriage in Philadelphia.
He is also expected to address the UN General Assembly in New York and meet President Barack Obama in Washington.
The announcement, at an interreligious conference on family values in the Vatican, was eagerly awaited after months of speculation.
Speaking at the Vatican on Monday, the pontiff said he would travel to Philadelphia for the "World Meeting of Families", a gathering sponsored by the Roman Catholic Church which takes place every three years.
The website of the conference said in a statement that Pope Francis would most likely travel there from 25 to 27 September, although dates are yet to be finalised.
Philadelphia Archbishop Charles Chaput, who had personally invited the Pope, said he was "overjoyed" by the announcement, adding: "A hallmark of his papacy has been a keen focus on the many challenges that families face today globally.
"His  charisma, presence and voice will electrify the gathering."
Pope Francis will become the fourth pope to visit the US, in a visit that Catholic officials say could draw up to a million people.
According to AP news agency, he had received invitations from President Obama, UN Secretary General Ban Ki-moon and Congress, as well as letters from more than 10,000 school children in Philadelphia, encouraging him to make the trip.
The Pope has announced plans to visit the US next September, his first trip there since his election last year.