In siding with the Crown, the Ontario Court of Appeal said the three-year sentence originally handed to the man was manifestly unfit and instead substituted a seven-year term.
"This case presented the court with a variant of the pattern of conduct of adult abusers in a position of trust over children," the justices said in their ruling.
"Here, the child was a teenager, but her extra vulnerability came from the fact that she was an immigrant to Canada...she was in his power in every way."
Ontario Superior Court Justice Cory Gilmore sentenced the uncle in June last year after a jury convicted him of sexual assault, sexual exploitation and invitation to sexual touching.
Evidence at his nine-day trial was that the girl came as a 15-year-old from Fiji to Canada in 1986 to get an education and lived with her uncle and aunt, whom she considered as parents.
At some point, the uncle, who can't be identified, began sexual improprieties with the girl that soon escalated from touching into sexual intercourse two or three times a week.
"The trial judge believed it was important for sentencing purposes that she determine the number of sexual assaults that occurred and she did so," the Appeal Court said.
"She found that the sexual touching occurred in the mornings approximately 36 times in three months, and that sexual intercourse occurred four times per month over a 31 month period, amounting to approximately 124 times."
Court records show the uncle administered birth control to the girl, and told her that if she told anyone about the sexual activities, she would be deported to Fiji, a prospect she dreaded.
"She told the court that she felt helpless, dumb and stupid," the trial judge said.
The girl finally got so desperate to leave the situation, she asked her aunt to arrange a marriage for her, and she finally left for Vancouver in 1991.
In its assessment of the sentence, the Appeal Court had harsh words for the uncle, saying he had shown no remorse for taking advantage of the fact that the girl was young and vulnerable as a new immigrant.
It also decided Gilmore had erred by imposing a sentence at the lower end of the scale.
"These circumstances changed the course of (the girl's) life, resulting in a forced arranged marriage which turned out to be abusive," the court said.