Dave Hollis, executive vice president of worldwide distribution for Disney, revealed the animated film's storyline and title - Monsters University - at the Las Vegas CinemaCon convention.
"The film is a prequel that tells you a little bit about how [Mike and Sully] first met, attending Monsters University," Hollis said. "Obviously everybody knows at this point Mike and Sully are amazing friends - the best of friends - but as it turns out, in this story, that wasn't always the case.
"From the moment they met at university, they could not stand each other. This story takes you through the ups and downs, and how they overcame their own differences."
Monsters, Inc., featuring the voices of Billy Crystal and John Goodman, was Pixar's fourth feature-length animation and grossed more than $500 million at the worldwide box office.
Dan Scanlon is directing Monsters University, which is due to open in US cinemas on November 2, 2012 and in the UK on December 7, 2012.