Yak Yew Chee, who worked as a senior vice president at BSI Singapore, was also a private banker for Malaysian businessman Low Taek Jho.
Yak pleaded guilty to four of seven charges at Singapore's state court, and he was also fined S$24,000 (£13,497, €15,677), Reuters reported.
Two charges related to forging reference letters vouching for the Low family and two to turning a blind eye to hefty sums – allegedly proceeds from criminal conduct – coursing through BSI bank in Singapore.
Yak is now expected to assist the ongoing 1MDB money laundering investigation.
He is one of a number of former BSI Singapore employees to have gone on trial.
In May, Ravi Menon, managing director of the Monetary Authority of Singapore (MAS), said that “BSI Bank is the worst case of control lapses and gross misconduct that we have seen in the Singapore financial sector.
“It is a stark reminder to all financial institutions to take their anti-money laundering responsibilities seriously. Controls need to be robust, surveillance vigilant, and the management culture must emphasise professional integrity and risk consciousness.”
Earlier this week, deputy prime minister Tharman Shanmugaratnam confirmed that MAS has no rules against hiring ex-offenders for positions in the financial services sector.