The song's music video was directed by Brett Ratner and filmed in Beverly Hills, California. It serves as the sequel to the video for "It's like That", the first single released from The Emancipation of Mimi.
Beginning with the "It's like That" video, the protagonist is at her bachelorette party, where one of the guests reveals himself as a former lover (played by Wentworth Miller).
The video for "We Belong Together" begins the following morning, when the protagonist remembers her former boyfriend, as she is preparing for her wedding. As she marches down the aisle, the protagonist debates whether she belongs with her former boyfriend or her fiancé (played by Eric Roberts).
Once she reaches the altar and is about to be binded forever to her fiancé, she catches sight of her former lover who is watching the wedding from a distance, and she runs from the ceremony and into his arms, shocking everyone at the wedding.
She is finally free as she and her former boyfriend flee the garden and into his car, the wedding dress trailing behind her. They are together again. The video is also intertwined with scenes of Carey singing and dancing in a room.
It ends with Carey and her former boyfriend cruising away from the garden on his car while the priest comforts her fiancé.