Titled "Glass", the 46-year-old director says the film will be a clash of the storyline of his previous two movies.
Shyamalan took to Twitter to break the news.
"It's taken 17 years but I can finally answer the #1 question I get, 'Are you making a ------ sequel to 'Unbreakable' or what?'
"My new film is the sequel to #Unbreakable and #Split. It was always my dream to have both films collide in this third film (sic)" he wrote.
Anya Taylor-Joy will also return as Casey Cooke from the 2016 film.
Universal Pictures will release the movie on January 18, 2019.