By Agence France-Presse
The Nigerian and Malaysian were hanged after their last minute appeals were thrown out.
"A 38-year-old male Nigerian national, Chijioke Stephen Obioha, had his death sentence carried out on 18 November 2016 at Changi Prison Complex," the Central Narcotics Bureau (CNB) said in a statement.
Obioha, who came to Singapore hoping to be a footballer, was convicted of trafficking 2.6 kilograms of cannabis in 2008. Under Singapore law, anyone caught with more than 500 grams of cannabis can be sentenced to death.
A change in the law in 2013 meant that Obioha could apply to be re-sentenced, opening up the possibility of a life sentence, but he turned it down, the CNB said.
Just before he was to be hanged in 2015, Obioha's lawyer filed for a stay in execution, which was allowed by Singapore's highest court, marking the start of a legal rollercoaster which saw Obioha applying and withdrawing several legal options.
On Thursday, his lawyers launched a final bid to have his sentence commuted to life in prison but were turned down by a three-judge court.
Separately, the CNB also confirmed the execution of 31-year-old Malaysian Devendran Supramaniam, who was convicted of trafficking heroin.
He was arrested in May 2011 at Singapore's border checkpoint with Malaysia carrying 2.7 kilograms of a powdery substance that contained 83.36 grams of pure heroin.
Like Obioha, Devendran launched an eleventh-hour appeal on Thursday to stay his execution, but was turned down.
Singapore takes a strong stand against crime and imposes the death penalty on offences such as murder and drug trafficking.
But human rights groups, which have called on Singapore to abolish capital punishment, condemned the execution.
"By executing people for drug-related offences, which do not meet the threshold of most serious crimes, Singapore is violating international law," Rafendi Djamin, Amnesty International's director for Southeast Asia and the Pacific said in a statement Wednesday calling for a halt to Obioha's execution.
Singapore executed four people in 2015, one for murder and three for drug offences, according to prison statistics.
Malaysia also uses capital punishment, executing murderers and drug traffickers by hanging, a system which, like that in Singapore, dates back to British colonial rule.