Which Disney film was the first to be released in the Disney Digital 3-D format?

Chicken Little was the first Disney film released in the Disney Digital 3-D format.

Released on November 4, 2005, Chicken Little was a computer-animated adaptation of the familiar fable about a young chicken who mistakenly believes the sky is falling. Disney launched the film in a new digital 3-D process in a limited engagement of roughly 100 theaters, making it an important early milestone for modern digital 3-D exhibition.

The film also marked Walt Disney Animation Studios' first fully computer-animated feature. Its digital production and stereoscopic presentation helped demonstrate how animated movies could be prepared for digital projection and 3-D presentation at the same time.

A common mix-up is naming a later Disney or Pixar title such as Bolt, Meet the Robinsons, or Up. Those films helped popularize digital 3-D, but they came afterward. Another distinction is that Disney later converted older 2-D films, including The Nightmare Before Christmas, into 3-D; that was a different process from Chicken Little being released as an early Disney Digital 3-D title.