Leissner was found to have issued an unauthorised letter to a financial institution in Luxembourg in June 2015 vouching for Low Taek Jho, the Malaysian businessman at the centre of the US investigation into the fund.
Low, also known as Jho Low, is accused of siphoning off $529m (£343.6m, €495.4m) from the 1MDB fund to finance his lavish lifestyle.
Leissner, who is married to former US model Kimora Lee Simmons, also made false statement on behalf of Goldman Sachs without the bank’s knowledge.
The Monetary Authority of Singapore (Mas) announced it planned to issue a prohibition order (PO) against Leissner in December 2016, giving him an opportunity to state why a PO should not be made.
The regulator, however, determined that a ban of 10 years should be issued with effect from 13 March 2017.
Leissner is therefore prohibited from performing any regulated activity under the Securities and Futures Act and taking part, directly or indirectly, in the management of any capital market services firm in Singapore.
Mas also announced its intention to issue POs against three further individuals convicted in Singapore for their involvement with 1MDB.
Lifetime bans are expected to be issued against the former branch manager of Falcon Private Bank Singapore, Jens Sturzenegger, and former BSI Bank employee Yak Yew Chee.
The lifetime bans reflect the “gravity of their misconduct”, Mas said.
A ban of 15 years is to be handed to Yak’s BSI Bank colleague Yvonne Seah.
Sturzenegger, a Swiss national, was branch manager of the bank in Singapore between August 2011 and October 2016, responsible for the branch’s compliance.
In January 2017, he was convicted of failing to file suspicious transaction reports and disclose information about suspicious outflows from the bank. He also provided false information to Mas and CAD to cover up his relationship with Low.
Sturzenegger, the first westerner to be charged in connection with 1MDB, was handed a 28-week jail term and fined S$128,000 (£74,402, $90,567, €84,807).
At sentencing, judge Ow Yong Tuck Leong said that Sturzenegger had engaged in “persistent, deceitful conduct in lying” to the authorities.
Falcon Bank in Singapore was shut down by the regulator in October 2016 over its connections to 1MDB.