Convicted murderers in NSW will not be eligible for early release if they refuse to aid police in the search for the bodies of their victims.
NSW Premier Dominic Perrottet said the reforms - known as "no body, no parole" laws - put the rights and needs of victims' families front and centre.
The laws were passed by the NSW parliament on Thursday.
"Families deserve the dignity of saying their final goodbyes and we must do all we can to demand offenders give up their secrets and bring some closure to families and friends of victims," Mr Perrottet said on Thursday.
"These laws mean inmates convicted of a homicide offence who choose not to cooperate with police to locate their victims will not be given parole."
Corrections Minister Geoff Lee introduced the proposed "Lyn's law" to parliament's lower house last month.
The name refers to Lynette Dawson, the Sydney mother who was murdered by her husband Chris Dawson in 1982 as he pursued an affair with one of his high school students.
Dawson was convicted last month of murdering Ms Dawson. The body of the mother of two has never been found and her case sparked calls for the proposed changes.
Under the new laws, police would have to indicate to the parole board the timeliness and usefulness of the information provided.
"This legislation will help the families and friends of victims get the closure that they deserve," said Dr Lee.
"The law is just and it is fair and it gives victims dignity and respect."
Some legal experts such as Professor Luke McNamara, co-director of the UNSW's Centre for Crime, Law and Justice, said the proposal fitted a pattern of governments acting out of a sense of duty to victims.
"But in terms of meaningful effect there is a big question mark whether the stated goals of these actual laws is ever achieved," Prof McNamara said.
Similar laws in other states have not seen convicted murderers revealing the locations of remains, and Prof McNamara said it was "misleading" that governments could coax a change of heart through law.
But University of Sydney legal expert Arlie Loughnan said "these laws will incentivise prisoners who can help police find a body to do so".
The new laws will apply to all current and future offenders including convicted offenders not yet considered for parole.
