The 31-year-old will take over the role of bondage businessman Christian Grey after "Sons of Anarchy" star Charlie Hunnam dropped out earlier this month due to a hefty workload that prevented him from adequately preparing for the movie, reports Variety and Entertainment Weekly.
Author E.L. James confirmed the casting on Twitter, saying, "Welcome to #TeamFifty @JamieDornan1."
Dornan is known for playing Sheriff Graham and the Huntsman on ABC's "Once Upon a Time." He is from Northern Ireland and has also modeled professionally for Calvin Klein.
Dornan is set to star alongside Dakota Johnson, 24, who has been cast as Anastasia Steele, Grey's love interest.
In addition to his roles on "Once Upon a Time," Dornan also appeared in BBC's "The Fall" and "Marie Antoinette."
Shooting for the film adaptation of "Fifty Shades of Grey" is slated to begin in November, with a release in August next year.
ABC News and the Associated Press contributed to this report.