In a case that has fractured diplomatic relations between the two countries, Girone and fellow marine Massimiliano Latorre are accused of shooting the fishermen while protecting an Italian oil tanker as part of an anti-piracy mission off India's southern Kerala coast in 2012.
Girone has been living in the Italian embassy ever since, while Latorre was allowed to return home in 2014 for medical treatment after having a stroke. India's Supreme Court last week extended Latorre's home leave by five months.
The Hague-based Permanent Court of Arbitration, where the proceedings were moved to last year, has called on both countries to agree on the procedure for the marine's return, the ministry said in a statement, adding that it would liaise with India to try to ensure his speedy return.
“This is good news for the marines, their families and for the reasons maintained by the government and our legal team,” the ministry said.
But the ministry underlined that the court's decision “will not influence the progress of the arbitration procedures, which should decide if Italy or India has jurisdiction in the case.” The arbitration procedure could take another two to three years.
Prime Minister Matteo Renzi, who has been regularly flayed by opposition leaders for failing to get both men home, said the news was “extraordinary”.
"This really is a significant step forward which we have worked on with great dedication," he told reporters in Florence, while stressing "friendship and cooperation to the great people of India and to the Indian prime minister (Narendra Modi)".
Felici per il rientro di Salvatore Girone, confermiamo la nostra amicizia e la nostra volontà di collaborazione con l'India— Matteo Renzi (@matteorenzi) May 2, 2016
Italy initiated arbitration proceedings last year and in August the International Tribunal for the Law of the Sea (ITLOS) ordered India to suspend court proceedings against the pair.
The detention of the marines, the murder charges and the long wait for the case to be resolved are sore subjects in Italy.
Italy insists the oil tanker, the MV Enrica Lexie, was in international waters at the time of the incident.
India argues that the case is not a maritime dispute but "a double murder at sea", in which one fisherman was shot in the head and the other in the stomach.