The Tamara Drewe actor will take on the role of Bard the Grim (also known as Bard the Bowman) in the films, Deadline reports.
Bard is the son of King Girion of Dale, who was killed by the talking dragon Smaug. He is a skilled archer and will have a greater role in the second half of the Lord of the Rings prequel.
It has also been confirmed that Benedict Cumberbatch, whose role in the films was accidentally revealed by Martin Freeman last month, will voice Smaug. He will portray the character using motion capture technology.
Director Peter Jackson officially announced the titles of the two films last month. They will be called The Hobbit: An Unexpected Journey and The Hobbit: There and Back Again.
Evans has been in the running for several major roles recently, including the lead in The Bourne Legacy and Tom Buchanan in The Great Gatsby.