The 46-year-old Watanabe — who received an Oscar nomination for his role in "The Last Samurai" opposite Tom Cruise — tied the knot with Japanese film actress Minami, 41, according to a statement issued by the couple.
"We've both experienced rough seas, but we've now found tranquility and fortune," the pair said from New York, where Watanabe is based. "We want to keep supporting each other and sharing our time together."
Earlier this year, Watanabe divorced his former wife, with whom he has two children. Minami parted with her first husband in 2000.
The couple plan to hold a wedding reception in Tokyo, but have not decided on a date or place, according to the statement.
Watanabe, who worked mainly in Japanese films before 2003's "The Last Samurai," co-stars in the upcoming "Memoirs of a Geisha," which hits limited theaters Friday, and expands nationally Dec. 23.