Aurora Empowerment Systems was awarded the worst-employer award at Cosatu's national congress on Thursday.
"They have broken every record in terms of dodging responsibility. They have starved workers; they have switched off electricity in hostels," Cosatu general secretary Zwelinzima Vavi said.
"The winner of this category is Aurora," he told delegates at the Congress of SA Trade Unions' national congress.
On Wednesday, Vavi asked the media to tell the worst employers to collect their awards from Cosatu "so they can go back and rebuild relationships with the unions".
Other nominees were the SA Post Office, Vodacom, the Medupi project and the Eastern Cape liquor board.
The now liquidated Aurora, whose directors include former president Nelson Mandela's grandson Zondwa Mandela, was, as preferred bidder, appointed to take over the management of two of Pamodzi's gold mines in Gauteng and the North West after that company was liquidated in 2009.
Aurora was removed after the directors were accused of destroying the infrastructure at the mines and causing the loss of more than 5300 jobs.