Robbie (Adam Sandler) dreamed of one day becoming a big rockstar. But instead, he has become one of the most entertaining wedding singers in the town of Richfield. At Robbie's latest wedding gig, he saves the wedding toast from being ruined by the groom's alcoholic brother (Steve Buscemi), and catches the eye of a waitress at the function, named Julia. Afterwards, they both tell how they are engaged: Robbie to his girlfriend Linda (Angela Featherstone), and Julia to her boyfriend, Glenn (Matthew Glave). Noting Robbie's handling of the situation inside the wedding, Julia wants him to sing at her wedding, which Robbie happily agrees to.
Eventually, Robbie and Linda's wedding day arrives, and everyone is there, except for Linda. It soon becomes apparent that Linda has decided not to go through with the wedding, leaving Robbie heartbroken and despondent.
After the wedding is called off, Linda meets with Robbie, expressing her concerns of ending up being stuck in Richfield, married to Robbie, and raising kids in his sister's basement.
Robbie's brother Sammy (Allen Covert), attempts to get him to snap out of his misery, and play another wedding gig. However, Robbie's sour mood disrupts the wedding toast, in which he insults the bride's Father, and breaks into a dour rendition of the song, "Love Stinks." Julia meets with Robbie afterwards, hoping that he'll still play for her and Glenn's wedding. However, he now expresses doubt about participating.
Eventually, Robbie's spirits start to perk up, and he ends up doing a Bah Mitzvah with Julia acting as a waitress. After the festivities, Julia asks Robbie if he'll help her plan her wedding. Robbie agrees, and along with his brother Sammy, and Julia's friend Holly. They do everything from try wedding cakes, to hiring a limo driver (of which Sammy is the only one in town).
Robbie eventually goes out for a party with Holly, Julia, and Julia's fiance, Glenn. At the party, Robbie gets to see that Glenn is anything but a nice guy, as he notices Glenn has no problems ogling other women on the dance floor. After everyone leaves, Holly tries to hook up with Robbie, but soon sees that he likes Julia.
Robbie grapples with his feelings, and eventually decides to tell Julia his true feelings. However, upon arriving at her place, he sees her in a window, in her wedding dress, speaking into a mirror (unheard to Robbie, she is saying his name, practicing saying she's 'Mrs Robbie Hart'). Robbie then gets drunk, and stumbles back to a bar, where he encounters Glenn. Robbie attempts to punch Glenn, but gets hit instead. Arriving back at his place, he finds Linda there, and they both go inside.
The next day, Julia shows up, only to meet Linda, who claims she is 'Robbie's fiancee.' Julia then returns home to Glenn, and decides she wants to get married as quickly as possible. Glenn warms to this idea, and they decide to head off to Las Vegas.
Meanwhile, Robbie awakes to find Linda, who says she can adapt to being the wife of a wedding singer, but Robbie explains that he doesn't want to marry her.
Robbie attends another wedding the same day, and runs into Holly, who explains that Julia is going to Las Vegas. After pressuring Sammy for help, Robbie gets a plane ticket (in First Class), unaware that he is on the same plane as Julia and Glenn (who are in Coach Class). When he finds out, the people in First Class eagerly help him, with a little help from Billy Idol, who is also in First Class.
Robbie finally expresses his true feelings to Julia through a song, and eventually, the two are married.