Onitolosi Etuini Atiai Latu was found guilty ​by a NSW Supreme Court jury in 2018 of murdering his girlfriend Rhonda Baker in Liverpool in August 2016.
The Court of Criminal Appeal on Friday found no miscarriage of justice took place when the jury considered his "tendency" to act violently towards the woman.
Ms Baker, 26 when she died, suffered facial and rib fractures, a "caved-in" eye bone and one-centimetre deep cuts on her lips.
She died in hospital from a brain injury as a result of the multiple blows Latu inflicted to her head.
Latu appealed his conviction, claiming the use of tendency evidence was a miscarriage of justice.
The prosecution had referred to a series of emails between Ms Baker and Latu during the trial as evidence to establish that he had a violent tendency.
Ms Baker wrote in an email that Latu allegedly told her "you better shut the f*** up or I am going to cave your head in", the crown prosecutor told the jury.
The appeal was rejected on the basis that the trial did not show real chance or significant risk that the relationship evidence would be wrongly used, Justice David Davies said.
A forensic pathologist, Dr Istvan Szentmariay, had confirmed that one of Ms Baker's bones had "caved in" as a result of being assaulted by Latu.
The jury had also heard Latu's history of violence towards Ms Baker during their relationship.
An apprehended domestic violence order was issued at the end of April 2016 as a result of a person witnessing Latu assaulting Ms Baker in a car.
Latu will remain behind bars until at least August 2037 before being eligible for parole.
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