Mr Natuman was sentenced in the Supreme Court on Friday, after last month pleading guilty to a charge of conspiracy to pervert the course of justice.
He was sentenced alongside Aru Maralau, a former police commissioner, who was guilty of a charge of complicity to interfere with the court process and handed the same sentence.
The charges stemmed from a bitter dispute that engulfed the police force in 2014. Mr Natuman, as then-prime minister, ordered Mr Maralau, the then-commissioner, to stop a police team from investigating other high-ranking officers accused of mutiny.
