Mario's Dad is the father of Mario and Luigi, living with his wife and extended family in Brooklyn. He appears early in the story during a family dinner, where he openly expresses disapproval of Mario's decision to leave a steady job under Foreman Spike and start their own plumbing business. He tells Mario that he is bringing Luigi down with him, causing Mario to feel hurt and offended. This moment establishes him as a practical, skeptical figure who values security and worries about his sons' future. Despite his harsh words, his concern comes from a place of wanting what he believes is best for them.

Later in the film, after Mario and Luigi succeed in defeating Bowser and are celebrated as heroes, Mario's Dad fully embraces his sons. He tells Mario he was amazing and proudly announces to the crowd, "These are my boys!" This shows a clear change in his attitude, moving from doubt to pride and acceptance. He does not possess any special abilities; his role is that of a grounding family figure whose initial resistance highlights Mario's journey to prove himself. His key relationships are with his sons and his wife, and his development centers on overcoming his initial lack of faith in Mario's ambitions.