BoJack Horseman, a washed-up sitcom star from the 90s, attempts to revive his career by writing a tell-all autobiography. He hires Diane Nguyen, a thoughtful ghostwriter, to help him, but is dismayed to learn she is dating his cheerful rival, Mr. Peanutbutter. The season follows BoJack's struggle with writing the book, his self-destructive tendencies, and his dysfunctional relationships, all while grappling with his past and a desperate need for validation.

As BoJack works with Diane, he sabotages his freeloading roommate Todd's rock opera out of fear of being alone. He also reconnects with his former co-star Sarah Lynn, leading to chaotic drug use. BoJack's growing feelings for Diane become a central conflict, especially after he drunkenly steals the "D" from the Hollywood sign, which Mr. Peanutbutter uses to propose to Diane. Later, BoJack visits his dying former mentor, Herb Kazzaz, seeking forgiveness for a past betrayal, but Herb refuses, leaving BoJack emotionally distraught. In a moment of turmoil, BoJack kisses Diane, who is now engaged to Mr. Peanutbutter. Despite BoJack's attempts to sabotage their wedding, Diane and Mr. Peanutbutter get married. Diane finishes the book, which portrays BoJack negatively, leading him to fire her.

The season concludes with BoJack winning an award for Diane's book and landing his dream role as Secretariat. Diane suggests it is not too late for him to change, but she does not reassure him when he asks if he is a good person.

Season 1 of BoJack Horseman covers episodes 1-12. Here's everything that happened:

Season 1, Episode 1: The BoJack Horseman Story, Chapter One - BoJack, a washed-up sitcom star, is pressured to write a memoir to revive his career. He meets ghostwriter Diane Nguyen, but is dismayed to learn she's dating his rival, Mr. Peanutbutter. The episode sees BoJack struggling with the book and his dysfunctional relationships. It concludes with BoJack agreeing to work with Diane on his autobiography.

Season 1, Episode 2: BoJack Hates the Troops - BoJack's night is ruined at a bar, leading to a regrettable hookup. A muffin dispute with a Navy SEAL escalates into a media frenzy after BoJack says some troops are "jerks". He tries to apologize on Mr. Peanutbutter's reality show but makes things worse. The episode ends with BoJack beginning to tell Diane about his abusive childhood.

Season 1, Episode 3: Prickly-Muffin - BoJack reconnects with Sarah Lynn, leading to chaotic drug use and partying at his house. Princess Carolyn briefly becomes Andrew Garfield's agent. BoJack confronts Sarah Lynn, who acknowledges her self-destructive path and leaves. The episode concludes with Sarah Lynn singing from a space shuttle.

Season 1, Episode 4: Zoës and Zeldas - BoJack mentors Todd with his rock opera, but sabotages it, fearing Todd's success and departure. Diane's ex-boyfriend, Wayne, writes an article about Mr. Peanutbutter while trying to win her back, labeling her a "Zoë". BoJack is revealed to be a "Zoë," a cynical introvert. Todd's rock opera is ruined due to BoJack's manipulation.

Season 1, Episode 5: Live Fast, Diane Nguyen - Diane and BoJack travel to Boston after Diane's father passes away. Diane's family proves unsupportive, leading to her frustration. BoJack tries to comfort her, offering a letter from her pen pal. Todd's storyline involves a scam with Princess Carolyn. Diane realizes her family is a "sinkhole".

Season 1, Episode 6: Our A-Story Is a 'D' Story - BoJack, fueled by jealousy, drunkenly steals the "D" from the Hollywood sign. He enlists Mr. Peanutbutter to help dispose of it, but Mr. Peanutbutter takes credit for the theft and proposes to Diane with the "D". BoJack leaves Diane an honest voicemail confessing his feelings, but she deletes it after announcing her engagement. Todd, meanwhile, navigates gang politics in prison. The episode concludes with Diane accepting Mr. Peanutbutter's proposal and BoJack's feelings remaining unsaid.

Season 1, Episode 7: Say Anything - Princess Carolyn's agency merges, forcing her to work with rival Vanessa Gekko. BoJack, after a bender, tries to rekindle things with her, but she's focused on work. Todd fills in for BoJack in a bourbon ad. Princess Carolyn faces professional challenges and personal loneliness. The episode concludes with Princess Carolyn alone in her office on her 40th birthday.

Season 1, Episode 8: The Telescope - BoJack visits a terminally ill Herb Kazzaz to make amends for his past betrayal. Herb refuses to forgive BoJack, leading to a heated argument and the breaking of their symbolic telescope. The episode concludes with BoJack kissing Diane, Mr. Peanutbutter's fiancée, as a result of his emotional turmoil.

Season 1, Episode 9: Horse Majeure - BoJack schemes to sabotage Diane and Mr. Peanutbutter's wedding, hiring Esteemed Character Actress Margo Martindale for a bank robbery. Todd becomes Mr. Peanutbutter's driver and learns of the couple's doubts. BoJack meets Vincent Adultman. The episode concludes with Diane and Mr. Peanutbutter getting married, leaving BoJack depressed.

Season 1, Episode 10: One Trick Pony - BoJack acts in Quentin Tarantulino's movie, playing Mr. Peanutbutter. Diane finishes her book, which portrays BoJack negatively, leading him to fire her after she leaks chapters. Todd reveals he knows about BoJack's sabotage, straining their friendship. The episode concludes with Diane and Mr. Peanutbutter's wedding ceremony.

Season 1, Episode 11: Downer Ending - BoJack, fueled by drugs, attempts to rewrite his autobiography, leading to intense hallucinations and self-reflection. He confronts Diane, seeking validation as a good person, but she offers no reassurance. The episode concludes with BoJack at the Griffith Park Observatory, signing a book for a fan.

Season 1, Episode 12: Later - BoJack wins an award for his book and lands his dream role as Secretariat. Diane assures him it's not too late to change, prompting a fantasy of a life with Charlotte. The episode begins with a flashback to Secretariat's suicide. Diane doesn't answer BoJack when he asks her if he is a good person.