The city-state is currently in a lockdown due to the coronavirus pandemic, and therefore, Punithan Genasan had to be sentenced via Zoom over his role in a drug deal.
The case marked the first instance of Singapore imposing the death sentence remotely.
However, the handling of the case has come under fire from human rights groups.
Amnesty International said: "[The ruling is a] reminder that Singapore continues to defy international law and standards by imposing the death penalty for drug trafficking.
"At a time when the global attention is focused on saving and protecting lives in a pandemic, the pursuit of the death penalty is all the more abhorrent."
And Phil Robertson, Human Rights Watch Asia deputy director, told the BBC: "It's shocking the prosecutors and the court are so callous that they fail to see that a man facing capital punishment should have the right to be present in court to confront his accusers."
Although the majority of court cases in Singapore have been adjourned due to the pandemic, cases that are thought to be essential are now being held remotely.