Masuda joined Johnny's Entertainment in November 1998. During his junior days, Masuda backdanced for many of his seniors in the agency, such as KAT-TUN, and participated in many Johnny's junior photoshoots. In 2001, he was cast as a junior high school student in the sixth season of the popular Japanese drama 3-nen B-gumi Kinpachi Sensei. In 2003, he landed the starring role in the drama special Musashi. He also performed with the junior group Kis-My-Ft as the 'M' after Matsumoto Kohei's departure.
In late 2003, Masuda became a member of the J-pop group News to promote the Women's World Cup of Volleyball Championships. When News went on hiatus in 2006, he and fellow NEWS member Tegoshi Yuya formed the singing group Tegomass. The duo released the single "Miso Soup" in both Sweden and Japan. Masuda was allowed to further his acting experience in 2006 by landing various supporting roles in many Japanese dramas.
In late 2008, Masuda and the promoters of TU→YU formed a singing group to release the song "Soba Ni Iru Yo", which was featured in the product's commercials and released through the Japanese mobile phone network.
Masuda landed a role in the drama Rescue, which aired in January 2009.
In November 2009, Masuda acted in the stage play Ame no Hi no Mori no Naka (Inside a Rainy Day's Forest), with his first stage play leading role.
He is currently active in the group News as well as the subgroup Tegomass.