Magic Lantern will work with the site to further develop editorial strategy, enhance production capabilities and design video branding.
The two-phase operation will initially involve helping the website translate its editorial vision across online and video, but will ultimately result in an ongoing partnership between the two firms to develop "innovative and interactive" content.
Guardian Unlimited's in-house team will work with the company to manage and develop video services on an ongoing basis. But Richard Ayers, editorial development director of Magic Lantern Productions, emphasised that the project would only result in video content where it enhanced a news or feature item.
"This is not going to be a rolling news station in The Guardian style," he said. "Video will only be used when it can add a new dimension to a story. The Guardian is renowned for doing a lot around user-generated content and free comment, and we are working with it to continue that development."