Mr Buckingham, who has come under sustained pressure from party rivals to leave the NSW Greens over a 2011 sexual harassment allegation, made the announcement on Thursday.

He described the NSW Greens as a "toxic" organisation that had abandoned its core values.

"They're a revolutionary socialist party that don't reflect mainstream Australian values," he told reporters in Sydney.

"The NSW Greens are no longer focused on the environment, they are no longer the party that Bob Brown founded and I, in good conscience, can no longer be a member of that party."

He said there had been an "exodus" from the NSW Greens over the party's factional infighting and he urged other members to leave with him.

Mr Buckingham will run as an independent at the March state election for the upper house.

However, he also wants to team up with "like-minded, independent, real Greens" with an eye to winning lower house seats - including the Newtown electorate of his factional rival Jenny Leong.

Ms Leong in November used parliamentary privilege to demand Mr Buckingham resign over the 2011 incident which she described as "sexual violence".

Mr Buckingham denies any wrongdoing after he was accused of harassment by a party staffer. He's pointed to an independent investigation that recommended no adverse findings.

Mr Buckingham on Thursday also took a swipe at Australian Greens leader Richard Di Natale, who he said had failed to stand up for procedural fairness and natural justice.

"Richard Di Natale's failure to address that issue and respond I think is a black mark on his leadership," Mr Buckingham said.

He's hoping traditional Greens voters lamenting the party's internal power struggle will jump ship and vote for an independent.

Mr Buckingham said he was going of his "own volition", but he'd already been consigned to an unwinnable spot on the party's upper house ticket.

The national party this week had also backed calls by the state branch for the besieged MP to stand aside ahead of the 2019 poll.

Greens NSW co-convenor Rochelle Flood on Thursday said the party welcomed Mr Buckingham's decision to comply.

But party colleague Cate Faehrmann said Mr Buckingham should never have had to resign.

"Jeremy still has a lot to offer the people of NSW, particularly in this critical decade of climate action, and I wish him the very best in his next project," she said in a statement.

Australian Associated Press