The Green Party boosted its number of councillors by 29 in Thursday's election, giving it 89 nationwide.
Its most eye-catching success came in the London borough of Lewisham where its representation grew from one councillor to six. The party also won its first seats on Camden council - where two Greens were elected in the Highgate ward - Islington, Hackney and Southwark. It now has 10 councillors in the capital.
Four gains in Norwich, where it is the third largest political group, increased its number of councillors in the city to nine.
The party won its first seat in Bristol - by just seven votes - as well as winning extra councillors in Oxford, Sheffield and Stroud.
The Greens fielded a record 1,294 candidates, including 567 in London, claiming they would reap the reward of David Cameron's emphasis on environmental issues. Although they failed to hit their target of winning 100 council seats, the party's principal speaker, Caroline Lucas, said the results reinforced its standing as the fourth party in British politics. Ms Lucas said: "The public are turning to the only real alternative to the spin and sleaze of the Westminster parties. Our record speaks for itself - wherever Green councillors are voted in, the public see the results and want more.
"Green candidates have stood on a platform of a healthy local environment, decent local services and a strong local voice and this message has been well received . The rise of the Green agenda has resulted in attempts by the Liberal Democrats and the Tories to market themselves as environmentally friendly and ethical yet the Greens throughout this campaign have rightly drawn attention to their poor record on issues of social and environmental justice on a local level."