Franchise creator Sylvester Stallone tweeted the news on Tuesday.
"WILLIS OUT... HARRISON FORD IN !!!! GREAT NEWS !!!!! Been waiting years for this!!!!" the actor wrote.
Lionsgate Studios didn't comment on Stallone's remarks, but Ford's rep confirmed the news regarding the actor's inclusion in the film and added that the 71-year-old actor will play his own separate character and not Willis' famous character, Church.
Willis departure reportedly comes as a result of his unwillingness to work for less than a $1 million a day for four days work.
In addition to Ford and Stallone,"Expendables 3" will feature Jackie Chan, Wesley Snipes, Nicolas Cage and Milla Jovovich.
The film is due out on November 15, 2014.