After unexpectedly nabbing a spot in NSW Parliament for the Animal Justice Party on Friday, Mr Pearson suddenly has a much bigger audience for his political agenda – and perhaps even his music.

"I often sing. It's a hobby but I also do recitals for various charities … it's a healing thing for the mind, particularly when you're working in an area where you're seeing a lot of suffering and torment," he said, adding: "I might sing a few songs in Parliament."

Mr Pearson, 55, secured the 21st and final spot in the upper house after preferences were electronically distributed.

Animal Justice was in the running for the seat alongside the Liberals and the colourful No Land Tax party. The surprise result was attributed to strong preference flows from the Greens.

Mr Pearson, currently executive director of Animal Liberation Australia, was "pretty thrilled" to be elected.

"It's time to go shopping for suits. In the animal rights movement you don't often wear a suit when you're doing investigations and rallying for animals," he said.

Mr Pearson lives in a historic converted church in Newcastle, along with two cats, two dogs and chickens.

Animal welfare was an ethos his parents instilled in him during childhood.

"They were both always talking about having to … consider those who can't advocate for themselves, who don't have a voice we understand," Mr Pearson said.

He recalled a fishing trip with his father, who reeled in a catch and said: "Son, even though this fish is not screaming, it's suffocating. You have to cut the base of its head and put it out of its misery."

"That's when I was three."

The government will need only the votes of Fred Nile's Christian Democratic Party to pass most laws. But it may be forced to negotiate with Mr Pearson on issues other crossbench MPs do not support.

Mr Pearson will oppose a planned crackdown on activists who break into farms to secretly film suspected animal cruelty.

He will fight to address perceived cruelty in the kangaroo meat trade and seek a ban on battery egg farming. He also wants action against puppy farms, the high rate of animal euthanasia at pounds, hunting in national parks and mining projects that disturb animal habitats.

At each election, half the upper house's 42 MPs face election.

The government secured nine seats, Labor seven, the Greens two and the CDP and Shooters and Fishers Party one each.

The Animal Justice Party win heads off a potential legal challenge after an early hiccup with the state's electronic voting system meant the party was left off the "above the line" section of the ballot paper for two days.

No Land Tax plans to dispute the election result in both chambers on various grounds, but its chance of success is considered slim.

Despite being a lone MP in Parliament, Mr Pearson insists he will be a "strong voice" and will seek support from even the most unlikely of corners: the Shooters and Fishers.

"I'm going to start presenting to them some different arguments they may not have considered before," he said.

"I'm quite confident that as a representative for animals … I'll be able to bear fruit."