Graeme Reeves granted appeal against sentence
But Reeves, who was found guilty in 2011 of removing Carolyn DeWaegeneire's clitoris and genitals, has lost his appeal against his conviction.
The NSW Court of Criminal Appeal will now consider whether Reeves' sentence should be reduced.
Reeves was originally sentenced to three-and-a-half years jail with a non-parole period of one year, but the Director of Public Prosecutions appealed against the inadequacy of the sentence.
In February this year, the NSW Court of Appeal found the sentence to be grossly inadequate and re-sentenced him to five-and-a-half years, with a non-parole period of three-and-a-half years.
Reeves appealed to the Court of Criminal Appeal then the High Court in October.
The High Court on Wednesday said the appeal court had erred by failing to dismiss the appeal by not "taking into account evidence of Reeves' deteriorating health and the imminent expiry of his non-parole period".