Only last month did Ottawa confirm that the Canadian citizen was facing trial in Shanghai, seemingly confirming prior reports of him being taken to the Chinese mainland by authorities.
Ottawa said Canadian diplomats were barred from attending the trial. China has treated Xiao as a Chinese citizen, therefore without the rights a Canadian might have.
What did the court say?
The Shanghai court said Xiao and his investment firm, Tomorrow Group, were convicted of "illegally absorbing public deposits, breaching trust in the use of entrusted property... [and] illegal use of funds."
The firm, which has been linked to a series of anti-corruption prosecutions and seizures, took and misused billions of yuans, the court said.
According to the court, Tomorrow Group also committed bribery to evade supervision and seek illegitimate interests.
Such actions "disrupted the financial management order, [and] seriously endangered the country's financial security," the court said.
The court's statement added that Xiao and his firm pleaded guilty and cooperated with authorities in recovering what they had illegally acquired.
The disappearance of Xiao Jianhua
Xiao was allegedly abducted from his hotel in Hong Kong in January 2017 and was thought to have been returned to mainland China.
The reports fueled speculation that China's ruling Communist Party might be abducting people outside the mainland.
At the time, Hong Kong, which has a separate legal system, prohibited operations by Chinese police.
Before his disappearance, he was investigated amid a state-led conglomerate crackdown.
"After five years of quietly waiting, our family is still, based on my brother's strict instructions, putting faith in the Chinese government and Chinese law," Xiao's elder brother Xinhua told The Wall Street Journal in June this year.
Hong Kong: 25 years of Chinese rule
Since his disappearance, Chinese-Canadian relations have been strained.
Canada arrested Meng Wanzhou, the chief financial officer of telecoms giant Huawei in Vancouver, at the request of Washington. China then detained two Canadians. All three were released last year.