Yong Vui Kong was 19 when he was sentenced to hang in 2008 for smuggling 47 grams (1.65 ounces) of heroin into Singapore. Only an act of clemency from President Tony Tan can save him now after his third appeal was rejected.
"We dismiss the application as it has absolutely no merit on the law and on the facts," said chief justice Chan Sek Keong, who heads the three-judge Court of Appeal.
"We are unable to accept any of the arguments. Some are mere assertions while some are contrary to evidence," he added, reading a summary of the written judgement to Yong, who stood somberly as he faced the judge.
Yong, now 23, from eastern Malaysia's Sabah state, has also filed a second appeal for presidential clemency after his first bid was refused by the previous president, SR Nathan.
According to official figures, there were four executions in 2011, two of them for drug-related offences. From 2004 to 2010, there were 26 Singaporeans and 12 foreigners hanged.
Death by hanging, the only form of execution in Singapore, is mandatory for anyone caught trafficking more than 15 grams of heroin, 30 grams of cocaine or 500 grams of cannabis, as well as for murder.
In its latest report, Amnesty International said the wealthy city-state is one of seven countries, including Malaysia, India and Iran, that continue to have a mandatory death penalty for certain crimes.
Singapore officials have defended capital punishment as crucial in the fight against drugs.