Signorina Rottenmeier governs the Sesemann household in Frankfurt as governess and housekeeper, overseeing the care and education of Clara Sesemann, the wheelchair-bound daughter of a wealthy German businessman. Her strict approach demands unwavering order, discipline, and conformity to social rules. She perceives Heidi's free-spirited nature and lack of formal education as deeply disruptive, actively suppressing the girl's expressions of Alpine heritage by forbidding discussion or reminiscence of her mountain home to enforce assimilation into Frankfurt's rigid structure.

She consistently disapproves of Heidi's perceived lack of refinement, frequently correcting the girl's conduct regarding unfamiliar city etiquette. This extends to curtailing Heidi's expressions of homesickness and attempts to leave Frankfurt. She confiscates a kitten Heidi smuggled in to comfort Clara, though the butler Sebastian later secures the animal elsewhere. Her frustration intensifies when Heidi's severe homesickness triggers sleepwalking, events the household staff misinterprets as a ghost, causing significant alarm.

Accompanying Clara to the Alps, Signorina Rottenmeier openly displays discomfort with the rustic conditions, fear of animals, and concerns about mountain safety hazards. Her persistent disapproval and inability to adapt prompt Clara's grandmother to dismiss her from the household, entrusting Clara's care to Heidi's grandfather for the remainder of the visit. This departure concludes her role in the narrative.