In life, Rosita was the sister of Mama Coco's husband, Julio Rivera, making her Coco's sister-in-law and Imedla's daughter-in-law. Through Coco and Julio's marriage, she became the aunt of Elena and Victoria and great-aunt to Miguel, Rosa, Abel, Benny, Manny and Socorro. She is the largest of the deceased Riveras in terms of physicalilty and has the (metaphorical) heart to match; when everyone else was startled or freaked out by Miguel's ability to interact with them, Rosita's first reaction was to rush at her great-nephew (accidentally smashing through her dimunutive brother) and give him a big hug. Her photo on the family's ofrenda was surmounted by a plate of cakes, implying that she was a big eater and loved sweet things when she was alive. Rosita's first appearance in the film is at the cemetery where Dia de los Muertos is taking place, where she immediately runs to hug Miguel when he encounters them. He initially doesn't recognise her, but after taking a closer look identifies her from her photograph. She and Tia Victoria both notice that whilst Miguel doesn't seem entirely dead, he isn't quite alive either. When Tio Oscar & Tio Felipe arrive frantically shouting that Imelda couldn't cross over with them, the family decide to go to her to sort this out. The Riveras find her in the Central Station and a clerk explains that because Miguel was cursed as a family matter, all he needs to do is get his family's blessing to go home. When he breaks his promise to Imelda to never play music again, he tries to get the others to give him their blessing but all of them refuse as they wouldn't dare cross Imelda; Rosita actually hides her face with her hair when Miguel offers her the petal. When Miguel runs away, Imedla summons her alebrije Pepita to track him down. When they finally do locate him, he is found with Imelda's estranged husband Hector, whom she had banished from the clan after he left to play music and never came back. They are shocked to learn that Hector was in fact murdered by Ernesto de la Cruz and is fading away from being forgotten by Coco, the only living person who remembers him. The family infiltrate De la Cruz's Sunrise Spectacular concert to retrieve Hector's photo, where they fight briefly with Ernesto's security guards and Imelda manages to recover the photo before ending up on stage. To the utter shock of Rosita and Victoria, Imelda starts to sing and dance whilst evading the guards and De la Cruz himself. Before they can send Miguel back, Ernesto shows up and grabs the boy, threatening to kill him if the family don't back off. Noticing a camera next to her, Rosita points it at Ernesto and motions to Victoria to turn it on, showing the audience as Ernesto shamelessly confesses to have murdered Hector and stolen his songs before throwing Miguel to his apparent death off the edge of the building. Pepita saves him, fortunately, and the filmed confession results in Ernesto being reviled by the Land of the Dead. However, the photo is lost in the process and the Riveras watch sadly as Hector begins to fade completely whilst Miguel is sent back in the nick of time.However, Miguel manages to save Hector by revitalising Coco's memory and he is accepted back into the clan. One year later, they are joined by Coco herself and they all cross the bridge together to go to their family ofrenda, where they happily watch as Miguel plays them a song.