The bear was picked up by Animals Asia, a non-governmental organization, on Wednesday.
The female bear, named Sky by its new caretakers, had been locked up in a cage at the bile farm since it was a cub.
The bear was anesthetized and given a quick health check, which revealed that it was obese, weighing over 200 kilograms (440 pounds); and was suffering from dental issues due to being given a bad diet.
Sky will be moved to the Vietnam Bear Rescue Center at the Tam Dao National Park, just 75 kilometers (47 miles) north of Hanoi. She will be quarantined for 45 days before joining other bears at the sanctuary's semi-natural enclosures.
Animals Asia has thus far rescued a total of 199 moon bears and sun bears from farms in Vietnam. Currently 179 of these bears are living in the sanctuary, where they receive appropriate nutrition and medical care.
Vietnam is home to both the moon bear, also known as the Asian black bear, and the sun bear, both listed as vulnerable species by the International Union for the Conservation of Nature.
The extraction of bile from living bears is illegal in parts of Southeast Asia, including Vietnam, where it has for long been used as a remedy in traditional Chinese medicine.
Vietnam banned commercial bear bile extraction in 2005, but more than a decade later it remains a problem as farmers who owned bears prior to the ban were still allowed to keep them.
The government signed an agreement last July with animal activists to shut down all bile farms and free the remaining bears in captivity by 2020.
According to data from the Forest Protection Department, nearly 800 bears are still held captive in farms across the Vietnam, while the number of bears in the wild has dropped to just a few hundred individuals.