At their annual conference in Glasgow yesterday, Green members voted overwhelmingly for "full participation" in Yes Scotland, ending a four-month rift with the organisation. Co-convener Patrick Harvie MSP, who advocated the tie-up, said Yes Scotland had made "substantial progress" since its launch in May.
The decision means the Greens will have a seat on Yes Scotland's advisory board, helping to shape its campaign strategy.
However, the gathering at Maryhill Burgh Halls also agreed the Greens would campaign for independence in their own right, as well as with Yes Scotland, and would support a multi-option referendum, even though Yes Scotland wants a single Yes/No question in 2014.
The Sunday Herald revealed in June that the Greens had decided against joining Yes Scotland because they felt it was dominated by the SNP and not the cross-party "big tent" it claimed to be.
Since then it has created an advisory board chaired by former Labour MP Dennis Canavan, which includes former Socialist MSP Colin Fox and former Tory Tasmina Ahmed-Sheikh.
After the vote, Harvie said: "This ensures that Greens take a front-row seat in this exciting debate, promoting fresh and radical ideas on Scotland's future. Greens are not nationalists, and we're not motivated by devotion to one flag or the other. But we can see huge opportunities to make our country fairer and greener."
Despite backing independence, several delegates raised concerns about the Greens losing their identity inside Yes Scotland. Former MSP Chris Ballance said: "I don't want Alex Salmond's independent Scotland. The Yes campaign so far has been acting as an extension of the SNP."
Alastair Whitelaw, from Glasgow, who argued for a separate campaign vehicle, said: "I'm deeply concerned about the independence of the Scottish Green Party. We ought to keep ourselves out of the embrace of the SNP in this."
But most of the 100 activists supported being in Yes Scotland as a means of influencing its work, and promoting Green ideas. Maggie Chapman, from Edinburgh, said if the Greens didn't join they would be "ignored" and the party was kidding itself if it thought it could generate the same interest alone.
The conference underlined the Greens' differences with the SNP on policies for an independent Scotland. Members backed a new Scottish currency instead of the pound; an elected head of state instead of a monarchy; higher taxes on the wealthy; and immediate withdrawal from Nato.
Blair Jenkins, chief executive of Yes Scotland, said: "This extremely welcome development is a tremendous boost as we continue to build the largest community-based campaign in Scotland's history."
Canavan added: "I am thrilled that the Scottish Green Party has decided to play its part in the Yes campaign and I know they will play a key role in helping to deliver independence in 2014."