By Agence France-Presse
A scrum of journalists greeted Najib, 64, as he became the first ex-premier in Malaysia to appear in front of a judge.
A tired-looking Najib was escorted by around 20 police officers into a courtroom where security was tight, less than a day after he was arrested at his luxury home by officers probing how billions of dollars of state funds disappeared on his watch.
The arrest is the latest in a series of stunning moves by investigators that suggest the legal noose is tightening around Najib, his family and many of his close political and business allies.
Malaysia's state news agency Bernama said the former premier is expected to face more than 10 counts of committing criminal breach of trust linked to SRC International Sdn Bhd, an energy company that was originally a subsidiary of 1MDB, which Najib founded.
"Najib is the first (former) prime minister ever to be charged in court in the history of Malaysia," said Tian Chua, vice president of Parti Keadilan Rakyat, a key political party in the current ruling coalition.
"It signals a new era where no one in public office will be immune from punitive action if they abuse power," he added.
According to an investigation by the Wall Street Journal, $10.6 million originating from SRC was transferred to Najib's personal bank accounts, a fraction of hundreds of millions of dollars from 1MDB that was allegedly funnelled to him.
The newly appointed attorney general Tommy Thomas will lead the prosecution team, Bernama said.
Lawyers familiar with corruption cases told AFP they expect the charges to be read to Najib and a plea would be taken. His lawyers are expected to apply for bail.
Allegations of massive corruption were a major factor behind the shock election loss in May of Najib's long-ruling coalition to a reformist alliance headed by his former mentor Mahathir, who turns 93 next week.
A press statement issued by Najib's camp late Tuesday said the impending charges and other investigations "are politically motivated and the result of political vengeance" under Mahathir.
It vowed that Najib "will contest these charges and clear his name in court".
Najib and his allies are accused of plundering billions of dollars from the 1MDB to buy everything from US real estate to artworks.
Shortly after his downfall, a treasure trove of valuables was seized in raids on properties linked to Najib and his family -- including cash, jewellery and luxury handbags -- worth up to $273 million.
He and his luxury-loving wife Rosmah Mansor were questioned by investigators, as were his stepson Riza Aziz, whose firm produced the hit 2013 movie "The Wolf of Wall Street", and his former deputy Zahid Hamidi.