Johnson is attached to play Jack Hyde, another man who is pursuing Dakota Johnson's Anastasia Steele in the sequel, reported Aceshowbiz.
Jamie Dornan is returning as Grey, while Dakota is back as his love interest, Steele. They are joined by Kim Basinger as Elena, Grey's old flame, and Bella Heathcote as Leila, another of his ex.
"Fifty Shades Darker" is scheduled to hit theaters Stateside on February 10, 2017.
It's directed by James Foley, who is also attached to direct the third instalment entitled "Fifty Shades Freed". Niall Leonard, the husband of the book's author EL James, will script both adaptations.