MENAI MP Melanie Gibbons will not seek re-election to Sutherland Shire Council at the September 8 elections.
The state government is passing laws to ensure a person can only serve in one elected position, either Parliament or on a council.
Ms Gibbons, who is among 29 MPs forced to make a choice, said she was planning not to stand again for council.
"Holding two positions is seen by some people to be a conflict of interest or a conflict of time," she said. "I haven't experienced either, but that doesn't mean there is not potential for it to happen.
"For me, the jobs welded together and, being on the council has helped me to keep across a lot of developments in the shire, such as west Menai.
"It was really just another late night for me."
Under the legislation, councillors elected to State Parliament will not have to give up their council job at the next state election but 18 months later.
Local Government Minister Don Page said the legislation would bring NSW into line with Queensland, Victoria, South Australia and Western Australia. Mr Page said ratepayers were not getting "full value" from MPs who did the two jobs and it was also not fair on an MP's constituents.
Do you agree with the change?
