Creator C. H. Greenblatt, a childhood fan of Hanna-Barbera content, began developing the series in January 2020 alongside Unikitty! director Careen Ingle and former Harvey Beaks writer/storyboard artist Hannah Ayoubi.

Jellystone! is the first series to feature many of Hanna-Barbera's trademark characters like Yogi Bear and Huckleberry Hound since Yo Yogi! in 1991, and the first production after the closure of the Hanna-Barbera studios.

It is also the first television series to feature these characters without involvement from Hanna-Barbera founders William Hanna and Joseph Barbera, who died in 2001 and 2006 respectively.

Instead of recreating the characters' past adventures, Greenblatt and his crew decided to have every Hanna-Barbera character live together in a single town, altering some of their core traits to make them more likeable for modern audiences.

Some traditionally male Hanna-Barbera characters were changed to female for gender balance in the series, including Augie Doggie, Jabberjaw, half of Top Cat's gang, Snooper, Squiddly Diddly, and Loopy De Loop.

Voice actor Jeff Bergman confirmed he was voicing Yogi Bear among other characters for the series.

Unlike Greenblatt's previous shows which used traditional hand-drawn animation, Jellystone! was animated digitally with Adobe Animate by Cheeky Little Media in New South Wales, Australia and Snipple Animation in Quezon City, the Philippines.

Greenblatt said the series took inspiration from sources outside Hanna-Barbera, such as Walter Lantz Productions' Hickory, Dickory influencing the portrayal of Pixie and Dixie, and Blue Sky Studios' Ice Age character Sid.

Greenblatt compared the overall tone of the show to season five of The Simpsons, the point when that series shifted from a domestic sitcom to a wacky ensemble-cast show.

Greenblatt described the series as a 'love letter' to Hanna-Barbera but insisted it was 'not a nostalgia show,' despite filling episodes with classic character cameos.