In 1993, Jennings co-founded the production company Hammer & Tongs alongside Dominic Leung and Nick Goldsmith. The production company was primarily responsible for directing and writing music videos. Their music video for Radiohead's song "Lotus Flower" earned Jennings a nomination at the 54th Annual Grammy Awards.
As a member of Hammer & Tongs, Jennings directed a number films including the 2005 science fiction comedy film The Hitchhiker's Guide to the Galaxy.
In January 2014, it was announced that Jennings would write and direct an animated comedy film for Universal Pictures and Illumination Entertainment.
Sing was released in late 2016. Jennings also voiced the character for Miss Crawly, an elderly iguana employed as an administrative assistant.
