In The Super Mario Bros. Movie, the character referred to as Mom is the mother of Mario and Luigi and a member of their extended family living in Brooklyn. She is a warm and supportive presence in the household, shown to be the most encouraging family member regarding the brothers' ambitions as plumbers. During the family dinner scene, when other relatives express doubt about Mario and Luigi's new plumbing business, she offers them reassurance and expresses pride in their efforts. Her support stands in contrast to the more skeptical or mocking attitudes of other family members, such as the brothers' father and their uncles.

Mom appears at two key moments in the story: during the family dinner near the beginning of the film, and at the conclusion when Mario and Luigi return home after their adventure. Her role is primarily that of an emotional anchor for the brothers, grounding their Brooklyn origins and underscoring that they have people who believe in them. She does not possess any supernatural or combat abilities and is not present in the fantastical Mushroom Kingdom portions of the story. Her influence is felt through the brothers' motivation to succeed and make their family proud.

Her personality is defined by kindness, patience, and unwavering familial loyalty. She shows no signs of the strict or temperamental traits sometimes associated with the character in other Mario media adaptations. In the context of the film, her function is to provide a sense of normalcy and unconditional affection, which serves as a counterbalance to the high-stakes adventure the brothers experience after being transported into the pipe world. Her relationship with Mario and Luigi is the central emotional connection she has in the story, and she does not undergo any significant character development across the narrative, as she remains a steady, caring figure from beginning to end.