State Department spokesman John Kirby says the flag will be hung early Monday morning before a ceremony to mark the re-opening of the Cuban embassy in Washington and the restoration of full diplomatic ties.
The department's lobby features the flags of more than 150 other countries placed in alphabetical order. Cuba falls between Croatia and Cyprus in that arrangement.
Later on Monday, Secretary of State John Kerry will meet at the department with Cuban Foreign Minister Bruno Rodríguez after which they will hold a joint news conference, Kirby said.
Rodríguez will be in Washington for the upgrading of the Cuban Interests Section in the capital city to a full-fledged embassy. The U.S. Interests Section in Havana will also become an embassy on Monday, according to Kirby, but officials say the secretary is not expected to travel to Cuba for its dedication until early August.
The United States severed diplomatic relations with Cuba in 1961 and no Cuban foreign minister has visited the department since. President Barack Obama and Cuban leader Raul Castro announced in December that they intended to normalize relations between their two countries, former Cold War foes.
At the time it was hoped that could be accomplished by spring, but the process dragged on longer than expected with several issues requiring more time to resolve than anticipated.
One of those was the issue of access for American diplomats in communist Cuba to travel around the country and meet people.
Kirby acknowledged that Cuba remains a restrictive country, but noted that the U.S. has full ties with other such nations and American diplomats are able to work there.
"It is not a restriction-free environment, but we're comfortable that they will be able to do the job that they need to do," he said.