Najib, 72, is serving a six-year jail sentence after being found guilty of graft and money laundering in one of several cases he faces linked to the alleged theft of billions of dollars from 1Malaysia Development Berhad - a state fund he helped establish in 2009 while he was premier.
The Kuala Lumpur High Court allowed a request from Najib's lawyers to move the date forward during proceedings on Tuesday, Senior Federal Counsel Shamsul Bolhassan told Reuters. The decision had been scheduled for January 5.
The house arrest decision will now come four days before the High Court is due to hand down its verdict on December 26 in the biggest trial that Najib faces over the scandal.
The ex-premier is facing four charges of abuse of power and 21 money-laundering charges for receiving illegal transfers of about 2.2 billion ringgit ($532 million) from 1MDB. He denies the charges.
CLAIM OF ADDENDUM ORDER
Najib first mounted a legal bid for home detention in April last year following a pardons board decision to halve his prison sentence. The board was chaired by the former king.
Najib insists the board's February 2024 decision was accompanied by an addendum order issued by the king that allowed him to serve the remainder of his jail term at home.
The case was initially dismissed before being overturned by an appeals court, a decision that was upheld by the Federal Court, Malaysia's top tribunal.
The house arrest case has stirred intrigue in Malaysia, with multiple government authorities, including members of the pardons board, for months denying knowledge of a royal document although the former king's office confirmed it had been issued.
In July, a lawyer acting on behalf of the attorney general told the Federal Court he did not dispute the document's existence but was challenging the procedure by which it was being submitted as evidence.
Some 1MDB-linked charges against Najib have been dropped. He has denied all of the charges brought against him.
($1 = 4.1340 ringgit)
(Reporting by Rozanna Latiff and Danial Azhar; Editing by John Mair)
Rosmah Mansor (C), wife of jailed former Prime Minister Najib Razak, leaves the Court of Appeal in Putrajaya, outside Kuala Lumpur, Malaysia, 17 September 2025. The Court of Appeal has dismissed Rosmah Mansor’s appeal to recuse the High Court judge who presided over her corruption trial involving the 1.25 billion ringgit solar hybrid project in the state of Sarawak. EPA/FAZRY ISMAIL