Najib's lawyer said officers had searched the ex-leader's home and an apartment for over six hours as part of an investigation into money-laundering, but no arrests were made.
The new government, headed by 92-year-old Mahathir Mohamad who secured a stunning election victory last week, has vowed to probe allegations Najib oversaw the looting of a sovereign wealth fund.
"We have no indication yet if police will make any arrest." Najib's wife Rosmah Mansor, deeply unpopular due to her reported love of costly overseas shopping trips, was known to have a vast collection of designer clothes and handbags.
The search came just hours after politician Anwar Ibrahim -- a key figure in the alliance that swept to power, who had been thrown in jail under Najib's rule -- was released, triggering euphoric scenes.
It is an ominous sign for Najib, whose all-powerful ruling coalition was ousted after governing Malaysia for six decades.
The unexpected result has been blamed in large part on public anger over the scandal involving the fund, called 1MDB.
Najib established 1MDB and is accused of deep involvement in the looting -- charges he has repeatedly denied. Nearly $700 million had appeared in his personal bank accounts while billions more are unaccounted for.
Mahathir, who ruled from 1981 to 2003, came out of retirement to spearhead the anti-Najib campaign and has found himself back in the country's top post. He has ordered that Najib, his wife, and others linked to 1MDB be barred from leaving Malaysia pending investigations.
As word of the police presence circulated on social media, scores of journalists and citizens gathered at Najib's home, where they remained into the early hours.
Mimie Lai, 45, said she came to "see what happens to the ex-prime minister and all the scandals... involving him and his wife." "I feel that finally justice is coming, somebody heard... what the people are praying for," she said, adding that Malaysians wanted an end to widespread corruption that set in under the longtime ruling Barisan Nasional coalition.
In the hours before the raid, Najib went to a mosque for special prayers ahead of the Islamic holy month Ramadan, which begins Thursday in Malaysia.
Anwar's release captivated the nation, with ecstatic supporters and journalists mobbing him and shouts of "Reformasi" (Reform) -- his rallying cry -- ringing out as his motorcade raced through the streets.
The 70-year-old declared a "new dawn for Malaysia" and insisted he had buried the hatchet with old foe Mahathir, with whom he had joined forces to oust Najib.
His case has gripped Malaysia for two decades. He fell out dramatically with then ally Mahathir in the late 1990s and was thrown in jail on much-questioned charges of sodomy and corruption.
He was released after six years and helped to unite a hapless opposition but was thrown in prison again in 2015 in what critics said was another effort to neutralise him as a political threat.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)