Rosita is an anthropomorphic pig. She has light pink skin, slightly floppy ears, 3 pointed fingers on each hand, blonde eyebrows, green eyes, and darker pink freckles on her cheeks. She wears a pink buttoned short sleeved blouse, light blue pants, and small, pointed black shoes. During her and Gunter's performance of Shake It Off, she wears a sparkly black costume, which only exposes her legs, hands, and face, has pointed ears on the top, and a long feathery train on the back. She also wears black heels with her costume.
Along with being able to sing, Rosita also learns how to dance by just letting the music tell her body what to do. She is also a great constructor, as she is able to build multiple elaborate contraptions that do her housework and care for her family all in one night without any help. This is implied in the beginning of the movie when Norman asks her to fix the sink.
Rosita gave up her teenage musical dreams years ago, but yearns to be more than just a devoted mom to her twenty-five piglets. She rarely has a second to herself, so she finds her moments of freedom intersect with this passion for music. She embodies and embraces that singer in all of us who just belts it out when no one is looking.
Then, there are fliers that go around that proclaims $100,000 prize, causing a stir in the animal world and Rosita saw that flier and decided to tryout in the singing competition.
Having given up her teenage dreams in pursuing a career in music, Rosita is a loving mother to her twenty-five children and devoted wife to her overworked husband, Norman, working as a stay-at-home mom, handling all the cooking, cleaning, and a majority of the child-rearing. While she loves her family, she soon comes to a point where she feels she's in a rut and wants to be more than just a wife and mother, her love of singing persisting and wanting to take the chance she never got. Her family also does not recognize her talent, as her kids tease her when she sings and her husband is too tired most of the time to notice her
Her yearning comes to a head when she comes across a flyer for a singing competition hosted by Buster Moon, and she decides to audition. She sings Katy Perry's "Firework" for her audition, and she successfully earns a slot in the competition, although she is partnered up with the excitable Gunter for a dance routine, due to Buster thinking she "has a good set of pipes, but is boring to watch". She returns home, excited and eager to share her experience with her family, but her children are too unruly and Norman is too tired to listen. In order to attend auditions and care for her family, she constructs a vast assortment of contraptions that does her housework and take care of her family, such as getting them breakfast and putting them to bed, along with her recording specific dialogue, such as telling her husband where his keys are, her goodbyes for her children leaving for school, and her reading a bedtime story for her children, all of which is unnoticed by everyone and shows off her skills of engineering and fabrication.
Working with Gunter proves to be rocky, as Rosita is hesitant to dance and doesn't have the same passion for it as Gunter obviously does. She is shown to be caring and supportive to the other performers, as she, and Gunter, cheer Ash up after Lance cheated on her. Before she and Gunter go on stage to practice, Rosita also offers Ash some gum or candy from her purse. She also allows Johnny to practice before her, but she couldn't follow through with it due to Gunter. She apologizes to Johnny, saying she has no control. While trying to dance during her rehearsal of "Shake It Off", she falls on her face literally only a few seconds after the song begins. Rosita thinks she won't be able to do what Gunter does, to let loose and let the music tell her body what to do, saying that the fire died out a long time ago, and she leaves rehearsals glum. However, while grocery shopping, she is able to freely and passionately dance to "Bamboléo" by Gipsy Kings. This gives her the confidence to return to rehearsals the next day, much to Gunter's delight. However, during this one of her contraptions at home goes awry, and after she returns home after the destruction of Moon Theater, she finds her children and Norman hanging on the clothing line. She does return to Moon Theater to help fix the stage and leaves Norman to take care of the children. On the night of the show, she smiles at the sight of Norman trying to control the kids. Rosita and Gunter are the first to perform. They sing and dance to Taylor Swift's "Shake it Off", and at first the audience is laughing at its cheesiness, but the tone in the performance changes, with Rosita and Gunter changing into matching sparkly black costumes, and put on a great performance and dance routine, which shocks and surprises everyone, including Norman and the kids. Rosita and Gunter's performance is met with applause, and Rosita's children run up on stage to do so. Norman, completely blown away, follows them, and romantically kisses his wife as the curtains close. At the end of the movie, Rosita, Gunter, Norman, and Rosita and Norman's children attend the grand reopening of Moon Theater with the other characters.
“Norman, would you please tell them what a good singer I am?”
“Okay, here. There should be some gum or some candy in there somewhere. Just help yourself.”
–Rosita, offering Ash the contents of her purse to take her mind off her recent break-up with Lance