Written and directed by "Martian Child" filmmaker Menno Meyjes, the picture is scheduled to start shooting this year, The Hollywood Reporter said Thursday,
Phillippe, who has starred in "Gosford Park" and "Breach," will play a seventh-century Viking warrior named Thorfinn who invades Britain, along with his older brother, Hakon played by "Lord of the Rings" veteran Sean Bean.
Phillippe and Cornish also co-star in Kimberly Pierce's upcoming film, "Stop Loss."
Cornish, who was seen recently in the Russell Crowe romance, "A Good Year," also has a role in the upcoming, "Elizabeth: The Golden Age."
Meyjes, who is ompleting post-production on his bio-pic of Spain's iconic matador, "Manolete," describes "Dreamer" as "a love story written in fire and blood."