Najib Razak, Malaysia’s Former Prime Minister, Loses 1MDB Appeal and Is Sent to Prison

The 69-year-old Mr. Najib, who remains an influential figure in Malaysian politics, denied wrongdoing throughout the proceedings against him. On Tuesday, he appeared in court with his wife and three children and delivered a lengthy statement before the ruling, saying that the court had treated him unjustly. “At the final stage of a case, it is the worst feeling to have, to realize that the might of the judicial machinery is pinned against me in the most unfair manner,” he said.

The court’s five-member bench unanimously dismissed Mr. Najib’s appeals and affirmed his conviction and sentence, said Federal Court Chief Justice Tengku Maimun Tuan Mat. “The defense is so inherently inconsistent and incredible that it has not raised reasonable doubt on the case,” she said.

Prosecutors accused Mr. Najib of being behind a sprawling multinational fraud scheme involving 1Malaysia Development Bhd., known as 1MDB, the country’s state investment fund. Investigators in Malaysia and the U.S. alleged Mr. Najib and his associates pilfered billions of dollars from the fund while he was in office.

The dismissal of Mr. Najib’s appeal and his immediate imprisonment may repair some of the damage the scandal, which spanned multiple jurisdictions, did to Malaysia’s international reputation. While others have been prosecuted for their involvement in the 1MDB fraud, Mr. Najib was accused of being the political figure at its center.

“The perception has been that people in senior positions of political power can get away with their crimes,” said

Bridget Welsh,

an honorary research associate at the University of Nottingham Malaysia. “Most Malaysians didn’t believe this would ever happen. It’s a good day for justice in Malaysia.”

The scandal led to calls for Mr. Najib’s resignation and his ultimate defeat in elections in 2018, when he was trounced by political rivals who later revived investigations into his alleged financial misconduct. He has since faced 42 criminal charges in five separate cases, most of which are still before the courts.

The decision Tuesday was tied to a case that was the first against him to result in a conviction, and involved allegations that roughly $10 million was transferred from a former 1MDB unit called SRC International Sdn Bhd. into his personal bank accounts.

Tuesday’s ruling ended Mr. Najib’s last avenue of judicial appeal, though he could still be freed by a royal pardon. His political party, the United Malays National Organization, has regained some popularity after its defeat in 2018, which ended its six consecutive decades in power. After Mr. Najib lost the premiership he continued serving as a member of parliament, but now that his conviction has been upheld he is barred from holding his current seat and making any future runs for office.

“This sends a clear signal about where the judiciary stands when corruption is concerned, and that it doesn’t matter who is accused—whether they’re a big fish or a small fish,” said

Malik Imtiaz Sarwar,

a senior lawyer involved in constitutional and public interest litigation. “It’s really an underscoring of the ‘without fear or favor’ principle.”

Malaysian authorities say Mr. Najib oversaw the plunder of 1MDB, which he controlled and expanded after being elected prime minister in 2009. The U.S. Department of Justice said more than $4.5 billion was stolen from the fund between 2009 and 2015 in an elaborate scheme that involved bribing officials in Malaysia and the United Arab Emirates to obtain lucrative deals and raise money for the fund, and laundering the loot through luxury real estate, artwork and Hollywood films.

Mr. Najib had a close relationship with Malaysian financier

Jho Low,

the plot’s alleged architect. Mr. Low, whose whereabouts is unknown, has denied wrongdoing. He faces more than a dozen criminal charges in Malaysia and the U.S., including money laundering and bribery. Malaysia’s Attorney General’s Chambers said in July that Mr. Low’s counsel sought a settlement, but the offer was rejected.

In 2018, a New York court charged Mr. Low and two bankers for the global investment firm

Goldman Sachs

with conspiring to launder billions of dollars and violate the Foreign Corrupt Practices Act. The bank has agreed to pay more than $5 billion to settle related lawsuits in the U.S. and Malaysia. One of the accused bankers,

Tim Leissner,

pleaded guilty. The other,

Roger Ng,

was convicted in April.

Civil lawsuits brought by the Justice Department since 2016 resulted in the return to Malaysia of more than $1.2 billion in seized assets linked to the scandal.

Mr. Najib himself was accused by Malaysian investigators of embezzling more than $680 million from 1MDB, some of which was siphoned directly into his personal bank accounts to bankroll his family’s ostentatious lifestyle. Raids on Mr. Najib’s properties in 2018 turned up more than $220 million worth of cash and valuables. Police said they seized a trove of necklaces, watches, tiaras and luxury handbags, some of which were stuffed with cash.

Mr. Najib’s wife,

Rosmah Mansor,

had famously expensive taste: Among the loot was her collection of Birkin bags, a costly line of purses by French design house Hermès.

Throughout his appeals, Mr. Najib cast the judiciary as biased and lodged multiple interventions that political analysts say appeared aimed at prolonging the proceedings—perhaps in hopes that a change of government could offer him a chance at clemency. His final petition to the Federal Court contained 94 grounds of appeal.

The court ruled that his complaints were devoid of merit.

“We can see delaying was clearly part of the tactic,” said Ms. Welsh, of the University of Nottingham Malaysia. “This is all part of a political narrative geared toward finding exit strategies for him.”

Write to Feliz Solomon at feliz.solomon@wsj.com and Ying Xian Wong at yingxian.wong@wsj.com