The deal was first reported by Jon Heyman.
Maeda, 27, plays professionally in Japan for the Hiroshima Toyo Carp of Nippon Professional Baseball. Maeda has a career record of 97–67, with a 2.39 ERA and 1,233 strikeouts.
Since his professional debut in 2008, Maeda has made three All-Star games, won three Golden Glove awards and captured the Sawamura award for best pitcher two times in his career.
Maeda had until Jan. 8 to sign with a MLB team or else he had to return to Hiroshima for one more season.
He asked to be posted twice before this winter, but his request was denied each time.