Photographers spotted the 29-year-old actress with the sling while running errands in Brooklyn, New York, but her representative has assured fans the injury is "nothing serious", reported New York Daily News.
"She had a minor accident over the weekend and injured her wrist," the spokesperson said.
The pictures surfaced the day after the trailer for her new film "Les Miserables" featured the actress singing "I Dreamed A Dream."
The movie is an adaptation of the successful stage musical based on Victor Hugo's classic novel set in 19th-century France, in which a paroled prisoner named Jean Valjean seeks redemption. Hathaway plays prostitute Fantine in the all-star movie musical.
Hathaway also stars in the highly anticipated "The Dark Knight Rises," which hits theatres July 20.