The bears were seized by the Wildlife Alliance from the Yung Wah II factory on Feb. 14 and brought to the Phnom Tamao Wildlife Rescue Center, The Phnom Penh Post reported.
Dean Lague, technical adviser for Wildlife Alliance's rapid rescue team, said his team was alerted to the bears' presence at the factory by former Yung Wah II employees.
"Having been fed only milk and rice [for a long time], they were chronically overweight, especially the adult male," Lague said.
The factory closed without notice in December, leaving about 7,000 people unemployed.
Soy Sokchea, a former worker at Yung Wah, said he believed sun bears had been kept at the factory about 10 years.
"The employer built cages for the bears," he said. "Not all workers were allowed to go and see them -- you had to be friends with the caretakers who let people in when the bosses were away."