Waterloo Road Reunited will focus on former characters from the drama, including Bolton, Michaela, Janeece, Philip, Aleesha and Paul.
The project is expected to include a mixture of episodes, fictional social media networks, fan sites and audio.
BBC Drama's multiplatform commissioning executive Sarah Clay said: "Unlike most dramas, Waterloo Road is unique in that every year popular characters have to leave the show because they leave school.
"This leaves Waterloo Road's massive online fanbase with a natural thirst to find out what happened to the likes of Bolton and Michaela. We wanted to give fans a chance to follow their lives online. The video will focus on events that bring the ex-pupils together, but the story extends beyond video, allowing the audience to follow their lives as if they were friends with them on Facebook."
Waterloo Road Reunited is scheduled to launch in Spring 2011. Waterloo Road is expected to return to BBC One in the New Year.