Set in Spain during the Age of Exploration, the film follow Jack as he discovers a world of giants hidden within clouds. Jack befriends the female giant Inma, who's "11 years old, 60 feet tall, fiery, feisty and a lot to control" and treats him like a living doll, Greno said. Meanwhile, the antagonists, Storm Giants, stand at 120 feet.
The film was officially announced on August 14, 2015, by John Lasseter, at the D23 Expo. The film is set to be a musical, with songs written by Kristen Anderson-Lopez and Robert Lopez, who previously wrote the music for the Academy Award-winning film, Frozen, in 2013. The pair won the Academy Award for Best Original Song for Let It Go. Dorothy McKim, who produced the acclaimed short, Get a Horse!, was announced as the producer of the film.
- This will be the second time "Jack and the Beanstalk" is adapted into a Disney Animated Canon film, making it the first ever fairy tale to be used more than once in the Disney Animated Canon, the first being the "Mickey and the Beanstalk" segment from Fun and Fancy Free.
- However, although the main inspiration for the movie is indeed Jack and the Beanstalk, Gigantic also draws inspiration from Jonathan Swift's Travels of Gulliver, especially for the plot point of a young Giant girl using the hero as a doll/pet, while in Mickey and the Beanstalk the story derived uniquely from the original tale.
- Tangled co-directors Nathan Greno and Byron Howard split up to direct their own features by themselves, both of which were originally slated to be released in 2016. Gigantic was pushed back to 2018 in 2015.
- The film was originally set to be entitled Giants.
- This will be the fourth computer-animated, musical, fairy-tale film of Disney, after Tangled, Frozen and Moana, respectively.
- This will also be the third Disney animated film to feature music from Kristen Anderson-Lopez and Robert Lopez, after Winnie the Pooh and Frozen.