But the court ordered a retrial after it adopted the prosecutors' opinion that they had found new evidence revealing the defendant was "very likely" to have played "an important role in the activities of drug smuggling".
Canada's government has said it has been following the case for several years and providing consular assistance, but could provide no other details citing privacy concerns.
On Saturday, a Chinese court will hear an appeal in the case of a Canadian citizen held on drugs charges, that could further test the tense relations between the two countries.
Meng Wanzhou, the chief financial officer of electronics giant Huawei Technologies, is wanted in the United States on allegations she lied to American banks as part of an effort to get around sanctions on Iran.
Schellenberg's trial comes amid reports in global media that another Canadian, Sarah McIver - who was taken into "administrative detention" for "working illegally" in China - has been released and has returned to Canada.More news: Putin oversees test of new hypersonic super rocket
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A Dalian government news portal said this week Schellenberg had smuggled "an enormous amount of drugs" into China.
An appeals court agreed with prosecutors who said Schellenberg was punished too leniently when he was sentenced to 15 years in prison on charges of being an accessory to drug smuggling.
Asked about the Canadian's detention at a press conference Thursday, Chinese Ministry of Foreign Affairs spokeswoman Hua Chunying said she was "not aware of the specifics of the case".
Both China and Canada say the McIver case has nothing to do with the other arrests.
The official website of the court released a statement on Wednesday saying the court will accept the appeal of the defendant Schellenberg at 2pm local time Saturday.
USA authorities claim Meng Wanzhou lied to US banks to get around sanctions against Iran asked to extradite the executive. Meng has said she is innocent.