Haruhi Fujioka, a scholarship student at the prestigious Ouran Academy, stumbles upon the Host Club, a group of wealthy, attractive boys who entertain female students with their charm and wit. While searching for a quiet place to study, Haruhi accidentally breaks an expensive vase in the clubroom. To repay the debt, Haruhi is forced to join the Host Club as a host, disguising as a boy due to her androgynous appearance. The club members, initially unaware of Haruhi's true gender, include the flamboyant twins Hikaru and Kaoru Hitachiin, the stoic Kyoya Ootori, the childlike Mitsukuni "Honey" Haninozuka, his protector Takashi "Mori" Morinozuka, and the self-proclaimed "king" Tamaki Suou.

As Haruhi becomes more involved with the Host Club, her down-to-earth personality and lack of interest in wealth or status set her apart from the other members. This contrast creates comedic and heartfelt moments as the club navigates various scenarios, from hosting themed events to dealing with personal challenges. Tamaki, the club's leader, develops romantic feelings for Haruhi, though he initially struggles to understand his emotions. The twins, Hikaru and Kaoru, often engage in playful antics, while Kyoya serves as the club's strategist and financial manager. Honey and Mori provide a balance of youthful energy and quiet strength, respectively.

Throughout the series, Haruhi's presence challenges the club members' perspectives on class, gender, and relationships. The narrative explores themes of identity, family, and societal expectations, often through humorous and exaggerated situations. The Host Club's interactions with Haruhi and their clients reveal their vulnerabilities and growth, as they learn to value genuine connections over superficial appearances. The series blends comedy, romance, and slice-of-life elements, creating a lighthearted yet meaningful story that resonates with a wide audience.