His departure had been expected ahead of an anticipated Cabinet reshuffle, and as AFP reported, he "replied 'yes' when journalists asked if he was taking part in his final Cabinet meeting on Wednesday after four years in the job."
Fabius is expected to be named head of France's Constitutional Council — the "top court making sure that bills comply with the constitution," The Associated Press reports. President Francois Hollande has formally nominated him for the job.
His successor has not yet been named. As the AP reports, "Environment and Energy Minister Segolene Royal and former Prime Minister Jean-Marc Ayrault, two of France's most experienced Socialist figures, are widely considered as favorites to take the position."
"As foreign minister since May 2012, Mr. Fabius has presided over some major foreign policy challenges at a time when his country has arguably become the United States' principal military ally in the fight against Islamic extremism.
"He helped push through the nuclear accord with Iran, notably holding out for tough conditions against the Iranians.
"France's activist foreign policy under his watch has also included several military interventions, notably in Africa — in Mali to combat Islamic extremists and in the Central African Republic to quell violent unrest after the country's longtime leader was toppled."
Fabius also was France's youngest-ever prime minister, serving from 1984 to 1986.
Separately on Wednesday, AFP reports that he accused Russia and Iran of " 'complicity' in the 'brutality' of [Syrian] President Bashar al-Assad's regime." He also criticized the U.S. "for a lack of commitment to resolving the Syrian war."