The series takes place in an animated world where anthropomorphic animals and humans live side by side. BoJack Horseman is a has-been, the formerly popular star of a fictional 1987 sitcom titled Horsin' Around, who devises a plan to regain his celebrity relevance with a tell-all autobiography. Ghost-written by BoJack's recent love interest, human Diane Nguyen, he dictates his troubled past expecting she will make him look good. BoJack's agent and on-again-off-again girlfriend Princess Carolyn is another life issue he must contend with, along with his freeloading roommate Todd Chavez, and his annoying frenemy/arch-rival Mr. Peanutbutter, who aside from starring on a competing 90s TV show with a suspiciously similar storyline, is also Diane's boyfriend (and eventual husband).
- BoJack Horseman (voiced by Will Arnett)
- Princess Carolyn (voiced by Amy Sedaris)
- Diane Nguyen (voiced by Alison Brie)
- Mr. Peanutbutter (voiced by Paul F. Tompkins)
- Todd Chavez (voiced by Aaron Paul)