During the thrilling 2011 International Championship of Collegiate A Cappella (ICCA) Finals at Lincoln Center, the all-female A Cappella group from Barden University, the Barden Bellas, takes the stage with high hopes. However, things take a turn for the worse when Aubrey Posen (Anna Camp) suffers an embarrassing moment and projectile vomits during her solo, resulting in a humiliating loss to their male rivals, the Barden Treblemakers. Humiliated, Aubrey and her co-leader, Chloe Beale (Brittany Snow), vow to lead the group to success after the departure of their previous leader, Alice (Kether Donohue).
Meanwhile, the ICCA commentators, John Smith (John Michael Higgins) and Gail Abernathy-McKadden (Elizabeth Banks), provide color commentary, with Gail expressing frustration over John's outdated views on female singing groups.
Fast forward four months, and we meet Beca Mitchell (Anna Kendrick), a Barden freshman who is less than enthusiastic about college life. Her strained relationship with her father, Dr. Mitchell (John Benjamin Hickey), forces her into higher education, despite her dreams of becoming a music producer in Los Angeles. As Beca works at the school radio station, she bonds with fellow freshman Jesse Swanson (Skylar Astin) and discovers more about herself through her Korean American roommate, Kimmy Jin (Jinhee Joung).
When Beca's father learns she isn't attending classes, he offers her a deal: if she joins a club and still wants to leave after one year, he’ll support her dream of moving to Los Angeles. At the campus activity fair, Aubrey and Chloe try to recruit new members for the Bellas but face a lack of interest due to last year's stage incident. Although Beca initially declines an invitation to join, after Chloe catches her singing in the shower, she can't hold back and convinces her to audition, showcasing Beca's vocal talent with a rendition of "Cups (When I'm Gone)".
Despite the initial reluctance from Aubrey, she realizes they need fresh talent and reluctantly accepts Beca into the group alongside other misfits: Cynthia-Rose (Ester Dean), Stacie Conrad (Alexis Knapp), Lilly Onakuramara (Hana Mae Lee), and Fat Amy (Rebel Wilson).
As tensions rise, it is revealed that Jesse and Bumper (Adam DeVine), leader of the Treblemakers, are both intertwined in the unfolding drama. The Bellas embark on a grueling practice schedule, yet Aubrey remains tied to outdated song choices despite Beca's modern suggestions. At their regional competition, a mix of old and new material leads to a respectable second place finish, sending them to the semi-finals.
After a chaotic confrontation with the Treblemakers results in Beca facing legal consequences, her relationship with Jesse begins to sour. Despite challenges, including Chloe's vocal surgery, Beca's determination prevails, leading to growth within the group when they rally to support her idea of fresh, modern music.
With the Bellas initially torn apart, they reunite to audition and adopt Beca's innovative style after a heartfelt conversation, culminating in Aubrey sharing leadership with her. After an unexpected turn in the Treblemakers' lineup, the stakes heighten as they prepare for the national competition.
As the momentous event approaches, the Bellas take the stage, performing a medley arranged by Beca that impresses the audience—and Jesse. The performance is not only a declaration of their musical evolution but also serves as a heartfelt apology, leading to a kiss between Beca and Jesse. In a triumphant conclusion, the Barden Bellas claim victory at the national competition, paving the way for future auditions as they look ahead with renewed hopes and ambitions.
