An hour before colleagues were set to vote to expel him from the NSW parliament, Kiama MP Gareth Ward resigned his seat amid widespread calls to kick him out.
The former families minister, 44, had resisted calls to resign as he awaits sentencing for sexually assaulting an intoxicated political staffer after a parliamentary event in 2015.
He was also found to have sexually abused a drunken 18-year-old man at his South Coast home in 2013.
A NSW District Court jury delivered the guilty verdicts in July and Ward was placed in custody soon after.
Ward has filed a notice of intention to appeal against his conviction.
Speaker Greg Piper announced Ward wrote to him on Friday morning to resign his seat, triggering a by-election at a soon-to-be-announced date.
Ward had launched a legal bid to cling to his seat, resulting in a vote to expel him from parliament being delayed.
But an injunction was dismissed by the NSW Court of Appeal on Thursday, paving the way for a parliamentary debate and vote on whether Ward should be removed.
"The fact that Mr Ward has filed a notice of intention to appeal does not affect the power of the assembly to expel him," Chief Justice Andrew Bell said.
Ward was also rebuked for launching the legal bid without providing proper notice and ordered to pay costs when the court handed down its decision on Thursday.
Following the decision, leader of the lower house Ron Hoenig gave notice of a motion to expel Ward "who is in custody, and unable to be present for the debate on the motion."
He withdrew the motion after the resignation.
"It is regretful that this house has been put through this difficulty but better late than never," Mr Hoenig said on Friday.
"(He has resigned) knowing full well what the almost unanimous decision of the house was going to be had he not tendered his resignation."
Opposition Leader Mark Speakman had repeatedly called on his former party colleague to resign from parliament, and has pledged support for any move to expel him.
Four MPs have been expelled from NSW parliament, the last in 1969, under the "unworthy conduct" power.
Ward won the Kiama seat as a Liberal in 2011, retaining it at multiple elections before leaving the party after charges were laid.
He won the seat again as an independent at the 2023 state election despite being suspended from parliament.
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