The Edward River Council Mayor was one of two candidates put forward for the internal party vote held in Deniliquin on Saturday.
The other was Leeton’s Sandra Williams, who is a long-time Nationals member.
Cr Betts said she was “excited and ready” for the challenge of running for state parliament.
“I feel honoured and privileged to be part of such an awesome team,” Cr Betts said.
“I'm really looking forward to hitting the ground running.
“We're going to give it absolutely everything, because as I said in there, I'm bloody determined to get this seat for the people.”
The NSW Nationals confirmed Cr Betts is one of only two preselection candidates last week, two days before the party voted in their Murray Electorate Preselection.
Although the idea of state politics is new to Cr Betts, she and her family have lived in the area for her entire life.
She is in her second term as an Edward River Councillor after being re-elected last year.
She has been mayor since January this year.
"I am passionate not only about my own community of Deniliquin, but also about our whole region,“ she said.
“I pride myself on building relationships with people from all walks of life.
"I like to listen to people and be the voice for people who feel they are not being heard or understood.“
In Deniliquin since Friday evening, NSW Deputy Premier Paul Toole attended the vote on Saturday.
He said Cr Betts was “exactly the type of candidate” the party and the people want.
“We're really excited to have someone like Peta Betts - someone who's born and bred in this local area, someone who's a local champion, someone who understands the issues of the local area, and someone who's going to fight for these communities,” he said.
"Having seen how strongly Peta represents her community as mayor, I know she will do the same for the entire Murray electorate.
“She's got a lot of attributes that we'd be very proud to have as a member of parliament, and I'm excited that she's come on this journey.”
With just over 100 days until the next state election, Mr Toole said he knows Cr Betts will be “working tirelessly across the electorate to ensure that those issues that people raise are being heard”.
“But also making sure that we take the seat back for the people of the National party,” he said.
“I think what's important here is to have someone who's actually going to raise issues, follow them through and actually want to see this electorate as a great place to live.
“All elections are different, but we'll certainly be throwing everything at this one to win it back.”
Cr Betts said she wants to make a difference and will continue to put regional people first.
“We do need better representation here and we want to be for the people,” she said.
“The only way to be for the people is to put my best foot forward and that's exactly what I intend to do.”