Born to a theater director father, Tetsuya Oguri, and having an actor brother, Ryo Oguri, Shun Oguri started his acting career quite early in his life. At the age 12, he started as a kid actor.
Oguri's debut role was playing the bullied and abused child Noboru Yoshikawa from the drama Great Teacher Onizuka in 1998, when he was about sixteen years old. His acting attracted him great attention and from there, he moved onto bigger roles. In 2000, he played a deaf person in Summer Snow. Two years later, he starred in the popular drama Gokusen, in which he played the part of a bully, rather than the bullied, as he did in Great Teacher Onizuka.
His brother Ryo Oguri and Shun performed together in the animation movie Fullmetal Alchemist the Movie: Conqueror of Shamballa, and the drama of Shakespeare's The Comedy of Errors.
His first lead role in a drama was in 2006 as Shinichi Kudo from Detective Conan. Oguri also lent his voice as a voice actor in Fullmetal Alchemist the Movie: Conqueror of Shamballa together with his brother Ryo Oguri in 2005. He also landed the role of Rui Hanazawa in the drama Hana Yori Dango, in which he once again acted alongside Gokusen co-star Jun Matsumoto. In 2007 he gained even more attention starring in the drama Hanazakari no Kimitachi e as Izumi Sano. In 2008, Oguri took up another lead drama role in Binbō Danshi, playing a poor college student named Kazumi Koyama. Oguri also played in the drama "Tokyo Dogs" as a lead role American detective.
He reunited with Hana Yori Dango co-star Mao Inoue for the drama Jūi Dolittle (獣医ドリトル Veterinarian Dolittle?), which began airing in October 2010.
Shun is also a full-fledged director, his first directorial debut was directing a commercial in 2009, but his first major directorial debut on the big screen was directing the movie titled Surely Someday, which was released in July 17, 2010 nationwide in Japan. Shun had cast several of his good friends within the entertainment industry in the movie such as Keisuke Koide as the lead starring role, Shun's other good friends actresses Mao Inoue and Aya Ueto also had cameo appearances in the movie. Shun himself also made a cameo appearance in the movie.