The Green Party is celebrating a gain of twenty councillors in England's local government elections.
Ms Lucas is one of the Green Party's principal speakers
Among its successes was the first election of a Green candidate in Bristol, and a record nine councillors for the party in Norwich.
Councillor Rupert Read called the four-seat Norwich gain "extraordinary".
The party already had 72 councillors and had targeted 100. Joint leader Caroline Lucas said the Greens had done "very well across the country".
She said the city council in Norwich - where former home secretary Charles Clarke is an MP - now has the largest Green group in England and Wales.
Mr Read said the gains gave the Greens the chance to have more leverage on issues such as affordable housing and stopping incineration.
"The people of Norwich have shown enormous faith in us, and we expect to reward them by going from strength to strength, and delivering the green policies that people so clearly want," he said.
Activists had been confident they would benefit from voters' disenchantment with the three main parties.
The Greens also said they had won votes from the emphasis placed on the environment by the Conservatives, Labour and the Liberal Democrats.
They particularly focused on the London boroughs of Lewisham - where they gained five seats - Hackney, Camden and Islington.
Councillor Darren Johnson, in Lewisham, said they were "absolutely delighted" with their success in the borough.