"Love Live! School Idol Project" centers on Otonokizaka High School, a school facing declining enrollment and the threat of closure. To combat this, second-year student Honoka Kosaka proposes forming a school idol group to attract new students by promoting the school's image. Inspired by the success of other idol groups, Honoka recruits her childhood friends, Umi Sonoda and Kotori Minami, to join her in creating μ's (pronounced "muse"), a nine-member idol group.

The narrative follows the group's formation, struggles, and growth as they aim to compete in the Love Live! idol competition, a prestigious event that could save their school. Each member brings unique traits and challenges: Honoka is energetic and determined but often impulsive; Umi is disciplined and cautious, balancing Honoka's enthusiasm; Kotori is kind-hearted and creative, serving as the group's costume designer. Other members include Rin Hoshizora, a tomboyish girl with a love for cats; Hanayo Koizumi, a shy idol enthusiast who gains confidence through the group; Maki Nishikino, a talented pianist initially reluctant to join; Nico Yazawa, a self-proclaimed idol veteran with a strong personality; Eli Ayase, the student council president who initially opposes the group but later joins; and Nozomi Tojo, Eli's close friend who provides spiritual guidance and support.

The series explores the challenges of balancing school life, personal struggles, and the demands of being an idol. Themes of friendship, perseverance, and teamwork are central as the members overcome obstacles such as self-doubt, conflicts within the group, and the pressure of competition. The story progresses through their journey from amateur performers to a cohesive unit capable of competing on a national stage. The Love Live! competition serves as the climax, testing their growth and determination.

The anime is structured into two seasons, with the first focusing on the group's formation and early performances, while the second delves into their preparation for Love Live! and the emotional stakes of their final year together. The narrative emphasizes the bonds between the characters and their shared goal of saving their school, culminating in a heartfelt conclusion that highlights their achievements and the impact of their journey.