Itō worked as background and creature designer on the survival horror video game Silent Hill in 1999. He was art director for its sequel, Silent Hill 2 (2001), working on both the original game and its reissue Restless Dreams, as well as being the chief monster designer/modeler. Itō was art director again in Silent Hill 3 (2003), as well as "drama camera designer".
The team disbanded with the release of the fourth game, Silent Hill 4: The Room in 2004 and for which Itō received a "Special Thanks" credit in the game. Itō and fellow Team Silent scriptwriter Hiroyuki Owaku went on to work together on Silent Hill: Cage of Cradle (2006), a digital manga published by Konami, downloadable for cell-phones and only available in Japan.
He maintains a personal website, complete with an online gallery of his Silent Hill-oriented artwork. Ito designed the cover art for the Japanese release of Silent Hill: Downpour (2012).
In 2012, Masahiro Ito stated on his Twitter that he would be willing to work on another Silent Hill game with Hideo Kojima.