Officers discovered 35 bags stuffed with cash at one empty apartment in Kuala Lumpur, and the banknotes were in 26 currencies.
Detectives also found 284 boxes of handbags in that property, and a further 150 handbags were seized from the home of Najib’s daughter, Nooryana Najwa.
Most of the handbags were by the designer Hermes – and other luxury items including watches, jewellery and baby shoes were also confiscated.
Five trucks were reportedly brought in by police to move the stash away from the scene.
More than a dozen properties have been searched since 18 May, including Najib’s home and the apartments of his son and daughter.
The former prime minister has been banned from leaving the country since he was defeated in an election on 9 May, with Malaysia’s new government reopening an investigation into billions of dollars missing from 1Malaysia Development Berhad (1MDB) – a state fund.
After more than six decades in power, Najib’s coalition was defeated by a reformist alliance led by his former mentor Mahathir Mohamad.
Public outrage over allegations of corruption linked to Najib was a major factor in the result.
The ex-leader, along with his family and friends, are accused of looting the state fund.
Najib led Malaysia for almost a decade, with he and the fund denying any wrongdoing. Three years ago, he said $680m transferred into his account had been a donation from an unnamed Saudi royal.
Pictures of the Hermes bags, a favourite of Najib’s wife Rosmah Mansor, have been sent to the designer’s offices in Paris so their authenticity and value can be verified.