Production notes

Writers Glenn Ficarra and John Requa conceived of Smallfoot, interested in a story about Yeti or Bigfoot; they drew inspiration from an original idea by Sergio Pablos. The concept for Smallfoot was in development before director Karey Kirkpatrick joined the project in July 2016; he viewed an animatic in which Percy was a "ski bum type" with no motivation on his personality in the first drafts of the script and repetitive gag lines, and so they added more elements in his later revisions by giving arc and depth to his character. Kirkpatrick also said Meechee was undeveloped, and she was made head of the S.E.S. in rewrites. Observing Brexit and a rise in nationalism, Kirkpatrick also drew inspiration:

Truth was under attack ... certainly phrases like alternative facts were being thrown around. So, it became an age of misinformation fueled by agendas that are often fueled by fear. And like, 'I want this result, and so I am skewing the truth.' That is just in the zeitgeist. On May 11, 2017, it was announced that the film was in-production with Channing Tatum, Zendaya, and Gina Rodriguez providing the lead voice roles. Ely Henry was originally hired as a scratch vocal for the film four years before its release, however was later invited to join the cast and subsequently voiced Fleem in the final product. The film was animated by Sony Pictures Imageworks, who had earlier been hired by Warner Animation Group to provide animation for Storks, and utilized Autodesk Maya for the animation process. Ryan O'Loughlin, a DreamWorks Animation veteran, was originally the film's director, but was replaced by Kirkpatrick.

The score for the film was composed by Heitor Pereira. The songs were written by Karey Kirkpatrick and his brother Wayne Kirkpatrick. The film originally had no songs until six months into production when the suggestion of making the film a musical came from Toby Emmerich, who was recently elected as chairman of the Warner Bros. Pictures Group at the time, partially because the Kirkpatrick brothers had previously written the music and lyrics for the Tony-winning Broadway musical Something Rotten!. The songs include "Perfection" performed by Channing Tatum, "Wonderful Life" performed by Zendaya, "Percy's Pressure" performed by James Corden (music from the song "Under Pressure", additional lyrics by Karey and Wayne Kirkpatrick), "Wonderful Questions" performed by Tatum & Zendaya, "Let It Lie" performed by Common, "Moment of Truth" performed by CYN, and "Finally Free" performed by Niall Horan (written by Horan, Ian Franzino, Andrew Hass, John Ryan and Julian Bunetta). The soundtrack peaked at number 8 on the Billboard 200. The song "Finally Free" peaked on a couple of Billboard charts including number 39 on the Mexico Ingles Airplay chart and number 2 on the Bandsintown X Billboard Top Livestream Artists chart.

Smallfoot grossed $83.2 million in the United States and Canada, and $130.9 million in other territories, for a total worldwide gross of $214.1 million. In the United States and Canada, Smallfoot was released alongside Night School, Little Women and Hell Fest, and was projected to gross $25–30 million from 4,131 theaters in its opening weekend. The film made $6.5 million on its first day, including $850,000 from Thursday night previews, more than the Warner Animation Group's previous September release Storks ($435,000 in 2016). It went on to debut to $23 million, finishing second at the box office behind Night School. It made $14.3 million in its second weekend and $9.1 million in its third, dropping 37% each time and finishing third and fifth, respectively.

On review aggregator Rotten Tomatoes, the film holds an approval rating of 76% based on 129 reviews, with an average rating of 6.3/10. The website's critical consensus reads, "Smallfoot offers a colorful distraction that should keep younger viewers entertained - and a story whose message might even resonate with older audiences." On Metacritic, the film has a weighted average score of 60 out of 100, based on 25 critics, indicating "mixed or average reviews". Audiences polled by CinemaScore gave the film an average grade of "A−" on an A+ to F scale, while PostTrak reported filmgoers gave it 4 out of 5 stars.