Oliver's first screen appearance was a supporting role in the 2002 Made-for-Television short film School's Out as Dean. He appeared in the BBC television series The Afternoon Play in the episode Girls' Weekend

In 2002, he was cast as the role of Ian Wallace in the teen romantic comedy What a Girl Wants. The film starred Amanda Bynes, Kelly Preston and Colin Firth and was directed by Denise Gordon. The film was released on 4 April 2003 to a mixed critical reception from critics. The film had moderate box office success earning worldwide a total of $50,732,139. He was the only actor to kiss Amanda Bynes in the screen test.

In 2004, Oliver was cast to portray the role of Jay Corgan in New Line Cinema's musical drama film Raise Your Voice. The film which was directed by Sean McNamara starred Hilary Duff and David Keith. The film was released 8 October 2004. The film received negative reviews from critics and was a box office bomb earning worldwide $10,411,980.

In 2006, Oliver signed on for the BBC drama television series The Innocence Project portraying the role of Nick Benitz. The eight episode first season received negative reviews from critics. Ratings were very poor and the BBC chose to pull the series midway through season one. A second season was not renewed.

In 2009, he portrayed the role of Ben in Paramount Home Entertainment's Without a Paddle: Nature's Calling. The film is a sequel to the 2004 film Without a Paddle. The film was released straight-to-DVD on 13 January 2009 to negative reviews.