Billy, played by Perry Fenwick, will come face-to-face with a number of sporting legends and celebrities in the spinoff episode, which centres around his upcoming Olympics storyline.
As first revealed last year, Billy will carry the Olympic torch through Albert Square in an upcoming episode of the main show. The footage will be broadcast live and direct from the show's Elstree base on July 23.
The Red Button special - titled 'Billy's Olympic Nightmare' - will air on July 16 in the build-up to the big moment, taking Billy from Walford to Wembley.
Viewers will see that Billy becomes nervous about his role of torch bearer, and his sleep is plagued by visions of what could go wrong.
When Billy finds himself running late for a series of special events at Olympic venues, he is grateful for the help of cab driver Hercules, played by comedian Omid Djalili.
Dame Kelly Holmes and Tessa Sanderson are among the well-known Olympic faces who will appear in the special, while One Show hosts Matt Baker and Alex Jones will also feature.
Fenwick told the official EastEnders website: "Like Billy, I am also terrified at what might go wrong as I carry the Olympic torch though Albert Square. Filming this was like a dress rehearsal of my worst nightmare!
"It was strange filming at West Ham as again, like Billy, I feel it's my home. I'm over the moon to be carrying the torch through Walford, and working with the likes of Dame Kelly Holmes has made me even more excited to do so!"
The Red Button mini-drama will become available to view straight after the regular EastEnders episode on July 16.
> 'EastEnders' Billy Mitchell to carry Olympic torch through Square
> 'EastEnders' Perry Fenwick nervous over Billy's Olympics plot
> Read more 'EastEnders' spoilers and news
Watch a preview of 'Billy's Olympic Nightmare' in the video below: