The Dalian Intermediate People's Court in China's northeast province of Liaoning re-tried Schellenberg, who had appealed his original 15-year prison sentence, and decided on execution, the court said.
Acting Foreign Minister Simon Birmingham said on ABC Radio on Wednesday the Australian government was "deeply concerned with this case". "We believe it is inhumane and inappropriate, and wherever the death penalty is considered with regard to a Canadian we speak out against it, " Freeland said.
Canadian Foreign Minister Chrystia Freeland said Canada has asked China to spare the life of Schellenberg.
China and Canada are embroiled in a worsening dispute, sparked by the arrest in Vancouver of Huawei chief financial officer Meng Wanzhou on a United States extradition request.
About a week later, two Canadian nationals were detained on suspicion of "engaging in activities harming China's national security".
China and Canada's diplomatic ties became strained, and concerns have been raised that Schellenberg's death sentence is being used as "payback".
The court said Schellenberg had conspired with others in an attempt to smuggle 222 kg (489.43 lb) of methamphetamine from China to Australia in late 2014.
China and Canada have also since traded new travel advisories, warning their citizens of the risks of travelling to the other country.
It warned Chinese citizens to fully evaluate risks and exercise caution when traveling to the country, given Canada's recent "arbitrary detention" of a Chinese national at the request of another country.
"We really understand how hard the situation is, and I think the Schellenberg family has our country's sympathy".
Chinese foreign ministry spokeswoman Hua Chunying gestures during a press briefing at the Ministry of Foreign Affairs building in Beijing on September 15, 2017.
China is urging its citizens to be cautious about going to Canada. China has continued to demand Meng's release, as its state media threatened consequences for Canada.
"We have very clearly outlined the case's facts and its seriousness", she told reporters.
Describing the case as "highly politicized, " the human rights group Amnesty International urged that Schellenberg's sentence be revoked.
Zhang said there was insufficient evidence to prove Schellenberg was part of a drug syndicate, or that he was involved in smuggling methamphetamines.
Asked whether it had concerns about due process, he said:"In China there is generally a problem of lack of transparency in trials".
She rhymed off a list of countries - Germany, France, the Netherlands, the European Union, the United States, Britain, Australia, Estonia, Lithuania and Latvia - for "publicly coming out and speaking against these arbitrary detentions".
A senior Canadian government official said Chinese officials have been questioning Kovrig about his diplomatic work in China, which is a major reason why Trudeau is asserting diplomatic immunity.