Three months after 28 activists and two freelance journalists were arrested at an Arctic oil platform, the Duma has voted for an amendment that extends an amnesty decree.
The activists, who have been charged with hooliganism, are now waiting on a final vote to grant them freedom.
Greenpeace said it looked to be only a matter of time until they can return to their families.
“The legal proceedings against the Arctic 30 are now almost certain to come to an end and the 26 non-Russians will be free to return home to their families as soon as they are given exit visas by the Russian authorities,” the organisation said in a statement.
Tasmanian activist Colin Russell and permanent Australian residents Alex Harris from Sydney and Jon Beauchamp from Adelaide have expressed relief at the vote.
“I know Colin Russell is desperate to get back to Tassie and return to a normal life after this extraordinary ordeal which has been so taxing for him, his wife Chrissie and daughter Maddy,” Greenpeace Australia Pacific Senior Campaigner Reece Turner said on Wednesday.
Mr Turner said Ms Harris was looking forward to the simple things when she returns to Australia.
“When I was in St Petersburg recently I asked Alex Harris, who works in our office, what she was going to do first when she’s back home in Australia.
“She said apart from seeing her friends and her dear cousin Gemma she was really looking forward to walking along Manly beach as a free woman.”
The group of environmental activists were imprisoned in September after protesting against Russia’s Prirazlomnaya oil rig in the Arctic.
The captain of the Arctic Sunrise, Peter Willcox said he should never have been charged and jailed in the first place.
“We sailed north to bear witness to a profound environmental threat but our ship was stormed by masked men wielding knives and guns.
“Now its nearly over and we may soon be truly free. But there’s no amnesty for the Arctic,” he said in a statement.
Greenpeace said it was unclear when the non-Russians in the group, including Mr Russell, would be able to leave the country.
Earlier this month 26 of the activists from 17 nations had their passports returned to them but they do not have the correct visas to leave Russia.
Greenpeace said the campaign to free the Arctic 30 has involved 860 protests in 46 countries.
Meanwhile more than 2.6 million people wrote to Russian embassies, the organisation said.