The hapless East Londoner, who is portrayed by actor Perry Fenwick, will be granted his long-term wish when he runs the torch through fictional Albert Square on July 23 next year, just before the Olympic opening ceremony on July 27.
Fenwick told The Mirror: "When we first discussed the storyline, my initial thought was that I'll now have to get fit.
"While this may be a fictional one-off for Billy Mitchell, it's a real once in a lifetime opportunity for me and I am thrilled that Walford and Albert Square will be part of this amazing event."
Billy and fellow EastEnder character Fatboy (Ricky Norwood) were both initially in the running for the torchbearer role, but Fenwick won the opportunity.
London 2012 chairman Lord Sebastian Coe said: "Today's announcement is a great addition to the Olympic torch relay route. I'm sure the people of Walford will now start planning their celebrations to welcome the flame to Albert Square.
"Along with people right round the UK, the residents of Albert Square will be getting involved to make this their moment to shine."
During the 70-day Olympic torch relay, 1,018 communities will be visited and it will travel about 8,000 miles. David Beckham said earlier this year that he was "proud to nominate" sportswoman Gabriella Roseje as one of 8,000 torchbearers because of her "inspiring" work with young people from disadvantaged backgrounds.
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