Environmental lawyer Sue Higginson will fill the Greens' vacancy in the NSW parliament upper house when David Shoebridge leaves to contest the federal election.
Ms Higginson, a former solicitor with the Environmental Defenders Office, has been involved in some of the highest profile environmental litigation in the country, the party said on Thursday.
Mr Shoebridge welcomed the preselection result.
"Sue has a proven track record taking on corporate excess and environmental destruction both as an activist and a highly capable lawyer," he said.
Ms Higginson said her environmental law experience will serve her well in challenging the government, noting "this decade is crucial in our fight against climate change, the extinction crisis and inequality".
"The Greens are a serious and significant force of reason, accountability and justice in the NSW parliament," she said.
"I will work to ensure politics serves the needs of people and the planet."
The preselection result will be presented to the party's state delegates council for formal ratification on March 12.
