Liu Han is former chairman of energy conglomerate Sichuan Hanlong Group in the southwestern province of Sichuan, which owns stakes in Australian and U.S. mines. He disappeared in March 2013, temporarily disrupting deals to finance mine development in Nevada and Australia, before police announced he had been detained.
The death sentences for Liu Han and his brother Liu Wei were the first in trials of their 36-member gang by a court in the central province of Hubei, the Xinhua News Agency said.
Chinese President Xi Jinping has launched an anti-corruption crackdown that has ensnared senior politicians and influential businessmen.
Many of the Sichuan cases are believed linked to Zhou Yongkang, a former member of the Communist Party's Standing Committee, the country's ruling inner circle. He is now believed to be a target of the wide-ranging graft investigation.
The Liu brothers and their associates have been charged with 15 crimes, including murder, assault, illegal detention, blackmail and operating casinos.
Prosecutors say their criminal activities, dating back to 1993, helped them amass 40 billion yuan ($6.4 billion) in assets with businesses in finance, energy, real estate and mining, Xinhua has said.
The gang is accused in the deaths of nine people, five of whom were shot, according to earlier reports. Police seized hand grenades, a half-dozen submachine guns, 20 pistols and other firearms.
Liu Han ranked No. 148 in 2012 on Forbes magazine's list of the richest Chinese businesspeople, with a fortune estimated at $855 million. He told The Wall Street Journal in 2010 that an investor once shot up his car after suffering losses in a deal.
The group is accused of fostering ties with politicians in Sichuan that helped Liu Han win appointment as a delegate of the provincial advisory body for three terms, according to earlier Xinhua reports.
Among the accused are three officials in city-level police and prosecutors' offices in Sichuan, Xinhua said. It said Liu Wei's testimony showed the officials received money and gifts as well as weekly parties with illicit drugs.