Four Americans detained in Iran will be coming home and seven Iranians in US custody will also win their freedom in a breakthrough swap negotiated by the longtime foes, officials in both countries said.
As well, a fifth American was freed separately.
The news emerged as a landmark deal took effect on Saturday relieving sanctions on Iran in return for its progress in pulling back its nuclear program.
Washington Post reporter Jason Rezaian, former US Marine Amir Hekmati, pastor Saeed Abedini and Nosratollah Khosravi-Roodsari, whose name had not been previously made public, were freed from custody in Iran and were to be flown to Switzerland, US officials said.
US student Matthew Trevithick was released independently of the exchange on Saturday and already was on his way home.
In turn, the US will pardon or drop charges against seven Iranians - six of whom are dual US-Iranian citizens - accused or convicted of violating US sanctions.
Three were serving prison terms and now have received a commutation or pardon. Three others were awaiting trial; the last one made a plea agreement.
It's unclear if they will leave the US for Iran. They are free to stay in the United States.
In addition, the US will drop Interpol "red notices" - essentially arrest warrants - on 14 Iranian fugitives it has sought.
The announcement of the exchange came shortly before Iran was certified as having met all commitments under the nuclear deal with six world powers.
The release of the prisoners and the nuclear deal developments capped weeks of intense US-Iran diplomacy that took several unexpected turns after an Iranian ballistic missile test in October and then the detention on January 12 by Iran of 10 US Navy sailors and their two boats in the Persian Gulf.
Frederick J. Ryan, Jr., publisher of The Washington Post, said in a statement, "We couldn't be happier to hear the news that Jason Rezaian has been released from Evin Prison."
Hekmati's family released a statement saying: "We thank everyone for your thoughts during this time."
Trevithick's parents said he was freed after 40 days at a prison in Tehran. They did not say why Iran detained him.
Trevithick co-founded a research centre based in Turkey that assesses the humanitarian crisis in the area and travelled to Iran in September for a four-month language program.
According to the official IRNA news agency, the seven freed Iranians are Nader Modanlo, Bahram Mechanic, Khosrow Afghahi, Arash Ghahraman, Tooraj Faridi, Nima Golestaneh and Ali Saboonchi. It didn't provide any further details.
The lawyer for Mechanic, who has been jailed since his indictment last April on charges of illegally exporting microelectronics technology to Iran, said his client was "elated" to be pardoned.
"He's been incarcerated for nine months for a crime that he's just accused of but did not commit," said lawyer Joel Androphy.
