Walt Disney chief executive Bob Iger confirmed the news to CNBC, following speculation.
Screenwriters Larry Kasdan and Simon Kinberg are working on the projects, which Iger said would be based on ""great Star Wars characters that are not part of the overall saga".
Disney is planning to release the films during the same six-year-period as the new trilogy, which will kick off in 2015 with Star Wars Episode VII.
The seventh instalment of the saga will be directed by JJ Abrams, who counts hit television series Lost and the recent Star Trek films among his credits.
The last Star Wars trilogy - a prequel to the original films - was released from 1999 to 2005.
Last year, Disney bought Star Wars maker Lucasfilm for more than $4bn.