Robbie, portrayed by Adam Sandler, once dreamed of becoming a famous rock star, but instead, he finds himself as one of the most entertaining wedding singers in Richfield. During a recent wedding gig, he skillfully saves the toast from being derailed by the groom's inebriated brother (played by Steve Buscemi) and catches the attention of a charming waitress named Julia, brought to life by Drew Barrymore. They both confess that they're currently engaged: Robbie to his girlfriend, Linda (Angela Featherstone), and Julia to her boyfriend, Glenn (Matthew Glave). Impressed by Robbie's performance, Julia expresses her desire for him to sing at her upcoming wedding, to which Robbie enthusiastically agrees.
The day of Robbie and Linda’s wedding arrives, but to his dismay, Linda decides not to show up, leaving him heartbroken. Linda later admits to Robbie her fears about being trapped in a mundane life in Richfield, married and raising kids in his sister's basement. Meanwhile, Robbie's brother Sammy (Allen Covert) encourages him to move past his sorrow and accept another wedding gig. However, Robbie struggles with his emotions, leading to an awkward incident during a wedding toast where he insults the bride's father and performs a melancholic rendition of "Love Stinks."
Afterward, Julia approaches Robbie, hoping he’ll still play at her wedding, but he is filled with uncertainty. Slowly, Robbie begins to rebuild his spirits and finds himself performing at a Bar Mitzvah with Julia as a waitress. Following the celebrations, she asks him for help in planning her wedding, and eagerly, he agrees alongside his brother Sammy and Julia's friend Holly. They embark on an amusing journey of cake tastings and hiring a limo driver, with Sammy being the sole option in town.
As Robbie spends more time with Julia and her fiancé, Glenn, he witnesses Glenn's true nature when he openly flirts with other women. After the party, Holly makes a move on Robbie, but it becomes clear that his heart belongs to Julia. Struggling with his feelings, Robbie resolves to confess his love to Julia. However, upon arriving at her home, he sees her in her wedding dress, practicing saying, “Mrs. Robbie Hart,” which makes him retreat into a state of drunkenness.
The following day, with the accidental return of Linda claiming to be Robbie's fiancée, Julia finds herself rushing back to Glenn and hastens their wedding plans to Las Vegas. Meanwhile, Robbie realizes he doesn’t want to marry Linda and learns about Julia’s Vegas plans from Holly. Desperate, he manages to secure a First-Class ticket, blissfully unaware that he shares a flight with Julia and Glenn, who are seated in Coach.
With the support of encouraging fellow passengers and a surprise appearance by Billy Idol, Robbie finally finds the courage to express his love for Julia through a heartfelt song. In a joyous conclusion, the two find their way to each other, culminating in their very own wedding.
