In Sydney, aged 20, she was working for skin care company Dermalogica when her friends urged her to audition to be one of the beauties in the fifth season of a Shine Australia television series.
She had no acting experience, but proud grand-dad Bruce Tonkin said she had always liked performing for the family.
Beauty and the Geek is now showing in New Zealand, with the first episode tonight on TV3.
Miss Tonkin had two months off work earlier this year, while the show was filmed on a Fijian Island.
On the first day she thought the conditions were going to be rough and wondered if she had ended up in an episode of Survivor.
"I don't usually do camping."
But there was a surprise in store, and the crew and contestants actually lived in a beach house on the beautiful island. The beauties and geeks were a great group and she made some amazing friendships.
She said her geek partner, Matthew, was "the most nicest, loveliest guy I've ever met in my life". He was a 24-year-old science whiz who hadn't had a girlfriend for years and was very nervous at first.
"He was very brainy in chemistry and all that stuff. He tried to teach me but it just went in one ear and out the other."
Both of them grew through meeting the challenges, and she said they were still good friends.
She found reality TV easy, because there was no acting involved.
"You get to just be your complete self and people get to see the real you."
But being filmed was harder work than her paid job in Sydney.
"It was very tiring - very early mornings, very late nights, filming all day every day pretty much."
The series has already been shown in Australia, and Miss Tonkin became an overnight celebrity in Sydney. People talked to her and photographed her wherever she went.
She loved it and would now like more television work.
