NSW Premier Barry O'Farrell's "Get Clover" laws have backfired and the electorate of Sydney has sent a message it can't be bought, independent candidate Alex Greenwich has declared after his landslide by-election victory.
The Clover Moore-backed candidate eased past the Liberals' Shayne Mallard to win Saturday's poll, with voters punishing the NSW government for forcing the popular MP out of parliament.
In a resounding defeat for the O'Farrell government, Mr Greenwich improved on the Sydney Lord Mayor's 2011 election vote.
More than 48 per cent of people voted for the independent, and after preferences from the Greens candidate Chris Harris, Mr Greenwich's finished with a two-party preferred vote of just under 65 per cent.
A law introduced by the O'Farrell government prevents state MPs from serving in local government.
Ms Moore's forced resignation from parliament after her re-election as lord mayor in September led to Saturday's by-election.
Ms Moore and Mr Greenwich were mobbed by rowdy supporters at their campaign function in Kings Cross, with the crowd chanting both their names, and one man yelling, "Up yours, Barry".
Mr Greenwich told them his landslide win was proof Mr O'Farrell's laws had backfired, "because now there is two of us".
"I think Sydney sent a very clear message to Barry O'Farrell and his government tonight," the 31-year-old same-sex marriage campaigner said.
"It sent the message that Sydney can't be silenced. It sent the message that Sydney can't be bought.
"We all sent a very strong message that also Sydney is not a Labor seat, Sydney is not a Liberal seat, Sydney is not a Greens seat. Sydney is our seat."
Ms Moore thanked her supporters for getting behind Mr Greenwich, and described the result as a "wonderful outcome".
She said the victory was a "real rejection" of Mr O'Farrell.
"It tells him that whilst he's got his big majority, he should not interfere in people's democratic rights," said Ms Moore.
During the campaign Mr Mallard had tried to play down the likely impact of Ms Moore's exit from state politics, and at a sombre post-poll function in Surry Hills told supporters he was disappointed with the result.
"Obviously any candidate who's not successful would be disappointed," he said.
Transport Minister Gladys Berejiklian said swings towards Mr Greenwich were not a backlash against the "Get Clover" laws.
"We're the only major party that ran so everybody who normally votes for other parties, that went to the Greens or Alex Greenwich," she told AAP.
The Labor opposition, who did not run a candidate to maximise Mr Greenwich's chances, congratulated him on his victory.
"Sydney voters told Barry O'Farrell that he had no right to remove a democratically elected MP - whether he liked Clover Moore or not," shadow special minister of state, Walt Secord, said in a statement.
"They spoke clearly and unequivocally against Barry O'Farrell's high-handedness."
