The glamour model was registered to race for The Vision Charity and The Pituitary Foundation, but was advised against competing after physios determined that she would not be strong enough to withstand the punishing 26-mile route.
However, in a Twitter message supporting this weekend's participants, the 32-year-old confirmed her commitment to running in the capital next year.
She wrote: "Good luck to all runners doing the London marathon - you are all amazing people! After proper treatment on my knee I will do [it] next year xx (sic)."
Price clarified that fans can still sponsor her brother Dan, who is running the Boston Marathon on Monday.
Earlier this afternoon, Price used the social networking site to wish good luck to her one-time rumoured love interest Amir Khan ahead of his world championship boxing match against Paul McCloskey tonight.
Price also pulled out of the 2010 London Marathon on doctor's orders.