Tom Casey, the US state department spokesman, said on Tuesday that the visa allowed Khatami to make a private visit that would include giving a speech at Washington's National Cathedral next week and attending a UN conference in New York on September 5 and 6.
The Shia Muslim cleric would be the most high-profile Iranian to visit the US since Washington cut diplomatic ties with Tehran in 1979 when 52 Americans were held hostage at the US embassy there after the Islamic revolution.
"The visa for former president Khatami was issued approximately an hour ago and that is in keeping with the functions that he had outlined," Casey told reporters.
Khatami's reformist government ceded power last year to Mahmoud Ahmadinejad, the current president.
Washington accuses Iran of being the chief "banker" of international terrorism and of attempting to build a nuclear bomb.
Casey said there were no restrictions on Khatami's travel while in the United States and that US visas were also granted to several members of his entourage.
However, no meetings are scheduled between US officials and Khatami, he said.
While the United States views Iran as a state sponsor of terror, Casey said, the United States did not see all of its citizens as "terrorists" themselves.
"This is an opportunity in part for former president Khatami to hear the concerns of the American people," Casey said. "He is going to get some tough questions."