Police were called to the Orsa Zoo, which bills itself as "Europe's largest zoo for predators", shortly after 10:30 on Friday, after which emergency services spent several hours working to save the man's life.
"We have alerted people close to him, and can now confirm that the employee has died as a result of his wounds," Stefan Dangardt, from the local police in Dalarna, told Swedish news agency TT.
Anders Blomquist, chief executive of Grönklittsgruppen, which operates the zoo, said that the attack took place during a special activity where visitors can interact with the animals.
The enclosure was supposed to be empty, but the police said that the bear somehow managed to get in.
"There are signs that the bear dug its way in, got into the enclosure, and then mauled and bit the employee."
The family accompanying the zoo worker escaped unharmed and the bear was later shot by another zookeeper. According to the police, the man killed was 19 years old.
Only two people were killed by bears in Scandinavia between 1977 and 2012, and only 31 attacked, of whom the majority were young men out hunting, according to a report by the Scandinavian Brown Bear Project.