About a hundred supporters had gathered outside the court, with some shouting “Allahu Akbar” and “Justice for Najib.”
Najib, 69, was found guilty in July 2020 of criminal breach of trust, abuse of power, and money laundering for illegally receiving about $10 million from SRC International, a former unit of state fund 1Malaysia Development Berhad (1MDB).
Najib, who pleaded not guilty, was sentenced to 12 years’ jail and a 210 million ringgit ($46.84 million) fine.
Prosecutors have said some $4.5 billion was stolen from 1MDB - co-founded by Najib as premier in 2009 - in a wide-ranging scandal that has implicated officials and financial institutions around the world.
Najib, who faces several trials over the allegations, has consistently denied wrongdoing.
The ex-premier replaced his legal team just three weeks before his final appeal at the Federal Court began last week.
Najib has said that his right to a fair trial was at risk, after the court rejected multiple requests to postpone the appeal to allow his new legal team to fully prepare.
His previous lawyers had submitted a written petition ahead of the hearings.
In his submissions, Najib listed 94 reasons why he should be acquitted, including that lower courts had erred in some of their findings.
Prosecutors have said Najib was aware that the funds received in his account were proceeds from “an unlawful activity,” and had exercised his position as prime minister, finance minister and advisor to SRC International to obtain the funds.