Katelin McInerney has won the Kiama by-election in a Labor landslide, becoming the state electorate's first female MP.

The win was declared for Labor around 8pm on Saturday after McInerney had attracted more than 37% of the primary vote.

At the end of the night, after more than 44,000 votes - more than two thirds of the overall electorate - had been counted, McInerney held an unassailable lead and was ahead 63-37% on a two-party preferred basis.

Liberal rival Serena Copley was a distant second with 26.2% of the overall vote.

"What an amazing feeling," McInerney said in her acceptance speech. "Second time lucky," she added in reference to narrowly losing the previous election.

She paid tribute to the other 12 candidates for the "respectful and peaceful" nature of the campaign.

"Many people voted Labor for the first time. And many people voted Labor for the first time in a long time.

"I will be a strong advocate and a strong voice in the NSW Parliament, representing this community every day. The work starts today."

Community Independent candidate Kate Dezarnaulds had received just under 11% and Greens nominee Tonia Gray was tracking at just over 8%.

Don Fuggle (Legalise Cannabis Party) and Felix Nelson (Shooters, Fishers, Farmers) were the best of the minor candidates with 5.1% apiece.

Minns issued a statement to say his government would "continue to work to deliver a fairer NSW – rebuilding essential services, reinvesting in frontline workers and building a better NSW for all".

"I want to make clear, we’re proud of the progress we’ve made so far, but our whole Labor team knows there’s still a lot more work ahead," he said.

"My government views this result as an invitation to work even harder for the entire state.

"I want to thank the people of Kiama for putting their trust in Labor. We do not take that trust for granted.

"We promised if Katelin was elected, the people of Kiama would have a strong local voice inside government, fighting for better schools, better hospitals, and the infrastructure the community deserves.

"Kiama now has that voice inside government, and I know Katelin will be a fierce advocate for her community.

"We take seriously the message from voters that we need to do better. We know we have more work to do."

The fact that there are 13 candidates on the ballot paper is diluting the vote slightly for the four main frontrunners.

McInerney and her supporters have gathered at Albion Park Bowling Club for election night with Labor regaining the seat for the first time since 2011 when Gareth Ward claimed victory over Matt Brown.

Copley and the Liberal Party faithful are watching the count from Nowra Golf Club.

Ward held the seat for more than 14 years - for more than a decade under the Liberal banner and as an independent in recent years - until he resigned early last month before he could be expelled from NSW Parliament after being convicted of four sexual assault offences.

He will be sentenced next Friday.

Sunny spring weather greeted the voters on Saturday as they flocked to polling booths throughout the electorate.

Serena Copley voting in North Nowra.

NSW Premier Chris Minns visited Albion Park in the morning to lend his support once again to McInerney.

“I love when we run a positive campaign,” he said. “We’ve laid out our plan for the future (of the Kiama electorate).”

More than 60,000 people voted with more than a quarter doing so at pre-polling in the week leading up to election day.