The Glendale-based studio said Reitman will write and direct "Beekle," a movie based on the award-winning children's book "The Adventures of Beekle: The Unimaginary Friend." The book, written and illustrated by Dan Santat, received the 2015 Caldecott Medal.
"Beekle" is the first project put into development by Bonnie Arnold and Mireille Soria, the co-presidents of feature animation.
The pair was installed earlier this year after the studio's chief creative officer Bill Damaschke stepped down in the wake of a string of box-office misfires that caused steep losses and sharp decline in the company's share price.
DreamWorks Animation executives said landing Reitman for the job was a coup for the studio.
"His incredible ability to tell heartfelt character-driven stories with a signature comedic tone makes him the perfect choice to bring this beloved book to the big screen," said Arnold and Soria in a joint statement. "We immediately fell in love with the concept of 'Beekle' and know that Jason will create something truly special from this fantastic source material."
Animation represents a new medium for Reitman, whose films include the Academy Award-winning "Juno"; "Up in the Air," for which Reitman earned a Golden Globe Award for screenplay; "Thank You For Smoking" and "Labor Day."
The Montreal-born director is the son of renowned Canadian film producer and director Ivan Reitman.
Reitman had a personal connection to Beekle, an imaginary character who sets off on a journey in search of a friend.
"I was book shopping with my daughter, when a little tooth-shaped character in a paper crown stole our hearts," Reitman said in a statement. "His name was Beekle and I'm honored to now be adapting Santat's charming story into a feature film. I'm particularly proud to be working with DreamWorks Animation, makers of 'Kung Fu Panda,' the first film my daughter ever saw on the big screen."