Reza Zarrab, 33, a resident of Turkey who holds dual citizenship, was arrested March 19 and presented in federal court in Miami yesterday, the department said.
The Iranians -- Camelia Jamshidy, 29, and Hossein Najafzadeh, 65 -- remain at large.
"As alleged, these defendants conspired for years to violate and evade United States sanctions against Iran and Iranian entities," said US Attorney Preet Bharara.
The defendants are accused of conspiring between 2010 and 2015 to dodge US and international sanctions against Iran by hiding financial transactions carried out on behalf of Iranian entities.
"The charges announced today should send a message to those who try to hide who are their true business partners," said Diego Rodriguez, assistant director in charge of the FBI's New York office.