Gore man Shannon Russell Swain, 34, appeared in the Invercargill District Court on Friday and was imprisoned for two years and one month.
His jury trial began in September, but an 11th-hour change of heart saw him plead guilty before the victim gave evidence.
The court heard that between 2013 and 2018 the defendant molested the girl at least six times.
On one occasion he groped the victim while they were both in a car with others.
In 2022, Swain won the New Zealand Billiards and Snooker Association 2022 national snooker championships in Gore.
At the time, he said he "couldn’t be happier" to win the tournament.
In a statement to the court, the victim explained the devastating impact the crimes continued to have on her.
"The abuse took away my childhood, a time that should’ve been filled with fun, friends and care-free moments.
"It still haunts me every single day."
The victim was struggling in school and found it difficult to trust people.
"I can’t help but wonder if this is how I’m always going to feel: afraid, angry and alone.
"I don’t want this abuse to control my life, but sometimes I feel like it already does."
She urged the court to lock Swain up.
"I know that no sentence will erase what has happened to me, but I believe that a strong punishment will bring me some sort of closure."
The victim’s mother described Swain as "disgustingly toxic and evil".
Her letter to the court further detailed the profound and long-lasting impact the "hideous" offending had on her daughter.
"It breaks my heart to see her so burdened."
She explained her daughter’s biggest fear was that Swain would go on to inflict harm on other children.
Counsel Bill Dawkins argued for home detention as it would allow his client to better engage in rehabilitation.
He said Swain was now truly remorseful after being in denial for so long.
Judge Duncan Harvey acknowledged the "dreadful harm" that had been caused to the victim and her mother.
"Unlike you, they are likely to suffer the after-effects of your offending for many years."
He questioned whether Swain’s remorse was genuine after denying the charge for two years and maintaining his innocence to his peers.
The court heard the defendant was seeing a counsellor to address his crimes, but also had not admitted his offending.
Judge Harvey asked Swain to imagine how frightened the victim must have been.
"She had nowhere to turn."
He ordered Swain to pay the girl $10,000.
He was automatically placed on the Child Sex Offender Register.
