The actress will now develop the M.A. Larson books via her Pacific Standard company, and she is also attached to play a supporting role, according to The Hollywood Reporter.
A statement from Witherspoon reads: ""Finally, there is a princess story that reflects the values young women truly want to embody. These princesses are strong, independent and fierce... In telling their story, Larson has created a magical universe that everyone will love to get lost in.""
The Princess Boot Camp series is based around a school that shapes girls into young warriors.
Larson is filmmaker Mike Nichols' former assistant.