On its Twitter account, the environmental organization said the 16 had their cases officially closed by the St. Petersburg Investigative Committee.
The first was British national Anthony Perrett, who was pardoned Tuesday. The remaining activists were expected to have their cases cleared by the end of the day, RIA Novosti said.
The charges were lifted as a part of a widespread amnesty by the Russian parliament to mark the 20th anniversary of the Russian Constitution, the British newspaper the Telegraph reported Wednesday.
The "Arctic 30," were initially charged with piracy but later saw the charges reduced to hooliganism and were released on bail in November after they were jailed for two months for protesting oil drilling in the environmentally sensitive Arctic region near Murmansk, Russia.
The non-Russian members of the group had been living in a St. Petersburg hotel since they left jail, the Telegraph said, adding they would be free to leave Russia as soon as exit visas are obtained.