He began acting when he was a teenager and appeared in several films in the 1990s including Little Giants, Casper, Now and Then, Wild America, Idle Hands, and Final Destination.

He also portrayed the title character of the Eminem music video "Stan" and starred as Owen Elliot in The CW action spy drama series Nikita.

He made his film debut in Little Giants in 1994 and received wide recognition for playing the title role as a human boy in Casper the following year.

Sawa continued to work steadily in the 2000s by appearing in several independent films, including Extreme Dating, Shooting Gallery, Devil's Den, Creature Of Darkness, Endure, 388 Arletta Avenue, The Philly Kid, and A Resurrection.

[16][17] In June 2022, Sawa gave a lengthy interview to The Independent, where he said that he sought out roles in which the character smoked marijuana to help get away from his teen heartthrob status which began with Casper.