Jean-Noël Barrot gave no further details about the circumstances of Lennart Monterlos's release but called for of two other citizens held by Tehran on espionage charges to be freed as well.
On Monday, an Iranian court had acquitted dual German-French national Monterlos of espionage charges related to the recent 12-day conflict between Israel and Iran.
He had been arrested in Iran in June around the time of a surprise Israeli air campaign that exposed intelligence failures and killed hundreds of military personnel and civilians.
A statement from the French Foreign Ministry said Monterlos has been reunited with his family.
"I do not forget Cécile Kohler and Jacques Paris, whose immediate release we demand," he added in a post on X.
Iran detained the pair 2022 and subsequently aired what appeared to be a forced confession in which they admitted to spying for Israel on state television.
Iranian Foreign Minister Abbas Araghchi suggested last month that the two could be exchanged for Mahdieh Esfandiari, an Iranian woman arrested in Lyon in February on charges of promoting terrorism through social media.
Last month, a British couple, Craig and Lindsay Foreman, appeared in court in Tehran on similar espionage charges after being held since January.
Western governments and human rights organizations accuse Tehran of detaining foreign nationals to gain political leverage in disputes with Europe and the United States.
Iran rejects the allegation, saying such cases are based on legitimate security concerns.
France withdrew its case against Iran at the International Court of Justice (ICJ) over the detention of Paris and Kohler, the court announced last month without elaborating. It was unclear if the move indicated their release was approaching.