Najib, who was prime minister for nine years, had always maintained his innocence and had said the legal process was a way to clear his name.
His lawyers had argued that he was misled by Malaysian financier Jho Low and other 1MDB officials into believing that the funds banked into his accounts were donated by the Saudi royal family, rather than misappropriated from SRC as prosecutors have alleged. Low denies wrongdoing.
Judge Ghazali told the court it was "far fetched" to believe Najib could have been misled by Low.
Dozens of Najib supporters, gathered outside the courthouse for hours, called for the former premier to be freed and were seen offering prayers.
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Najib himself appeared calm, albeit stony-faced.
Since losing the 2018 election, Najib has enjoyed a resurgence in popularity after embarking on an extensive public makeover, adopting a more personable tone to replace his image as a wealthy elite.
His party returned to power in February as part of an alliance led by Prime Minister Muhyiddin Yassin.
The guilty verdict could boost Muhyiddin's credibility with the public, but create tensions within the coalition in which Najib's UMNO party is the biggest component.
Sources have said if Najib is found guilty, there's a real threat of his camp withdrawing support for the government, which has a razor thin majority.
