Eric Edelstein as Grizzly "Grizz", a grizzly bear and the eldest of the Bear brothers. Highly sociable yet socially inept, he among the Bears had the most desire to be accepted and loved by society and cares deeply for the well-being of his younger siblings.
Bobby Moynihan as Panda, a panda bear and the middle brother. A hopeless romantic, he often changes his online personality to be perceived as a "cool guy".
Max Mitchell as Baby Panda.
Demetri Martin as Ice Bear, a polar bear and the youngest of the Bear brothers. Monotonous and stoic, he always speaks in third person and one-liners and has a variety of skills which prove to be useful in situations.
Mitchell as Baby Ice Bear.
Marc Evan Jackson as Agent Trout, a Wildlife Control agent, intent on capturing the Bears and separating them from human society and themselves, who is later defeated and arrested by Officer Murphy.
Keith Ferguson as Officer Murphy, who is adamant about punishing the Bears for their antics. Ferguson also voices additional characters in the film.
Jason Lee as Charlie, a Bigfoot friend of the Bears, who is also a yoga instructor and helped free the bears from Trout after some help from Brenda and his animal friends.
According to We Bare Bears series creator Daniel Chong, he was approached by the Cartoon Network staff with an idea for a feature film based on the series in 2018.[1] Despite having no previous experience in film, Chong accepted the proposal, drawing from his feature animation practice and reasoning that the characters he created have an emotional depth in them and capabilities he knew that could be sustained for a long period of time. Due to the then-continuing production of the series, Chong and his team had to prepare the film while finishing the episodes at the same time, which took over several months. The film's story was written by Mikey Heller and Kris Mukai, the main writers of the series. While writing it, they were inspired by the 2018 California wildfires and the Trump administration family separation policy that were occurring at the time, which lead to a family being separated from each other as a central theme to a forest fire being written in the story's climax. Chong remarked that sensitive topic such as those wouldn't appear to be ideal in the main children's television series. He also wanted the main themes within the series to be displayed in the film, such as diversity and the reason for anthropomorphic characters.
Chong remarked that the original treatment of the film was centered around the three Bears. But to balance the heavy themes, the film's core was shifted to be centralized around Grizz. The original meeting sequence was first written with the three bears reminiscing it but was rewritten to be focused on Grizz, who, as Chong felt, as the eldest of the brothers, was faced with the heaviest burdens and was most concerned with everyone's well-being. Chong also remarked that he was initially opposed to the addition of the other captive bears, as it could risk the main characters as uninteresting. The film was finalized as the Bears' final adventure and a conclusion to the original We Bare Bears series, though Chong had expressed intentions for it to continue to spin-offs, among other different ways. This was before he announced that he'll be departing Cartoon Network to work on another project. The animation on the film was produced by Rough Draft Studios and Saerom Animation, which had previously animated the television series.
