Tran Duc Dat died from his injuries during the incident on board VP Petrochemical Transport’s 3,100-dwt VP Asphalt 2 (built 2013), officials say.
Pirates stormed the vessel yesterday morning as it made its way from Singapore along the east coast of Malaysia.
After shooting the crewman, they stole property from the crew before escaping, Noel Choong, head of IMB's Kuala Lumpur-based Piracy Reporting Center, told AFP.
The official says a Singaporean helicopter had attempted to rescue the seafarer but he died from his injuries.
Roy Paul, programme director at The Maritime Piracy Humanitarian Response Programme, said: “Again a seafarers life has been unnecessarily taken by brutal criminals and this has caused a great deal of devastation to the seafarers family and his colleagues in the maritime industry.
He added: “The attack on M/T VP Asphalt 2 was close to the position where M/V Sunrise was attacked recently on 2 October, 2014 and this needs very intense investigation and a rapid response now they have taken another innocent seafarers life.”
According to Bloomberg this is the 10th attack by pirates in the area this year. It is also the third on a Vietnamese ship in two months.
While the death marks the first in around two years in Malaysian waters, the rise of maritime crime in the region has been highlighted as a cause for concern.
Of the 178 pirate attacks in the first three quarters of 2015, 103 took place in South eastern Asia, Bloomberg says citing IMB figures.