It's understood to be the first time in Vanuatu that a person found guilty of murder has been jailed for that long.
The Supreme Court found Philip Jimmy guilty of the premeditated murder of Alice Karis.
In his judgement Justice David Chetwynd said there was a need to punish the defendant, in order to deter other men from using violence against women.
He said it was also about reinforcing the need to respect the equal rights of women, particularly in the context of a domestic relationship.
While the maximum sentence for murder is a lifetime sentence, the judge gave the defendant 26 years, saying he was a first time offender.
The victim's father, John Din Karis, told the Daily Post newspaper that he welcomed the judgement.
He said murderers had no place in a decent society and must be made to feel the full force of the law.