Moomin is the central character in the "New Moomin" anime. He is driven by inherent curiosity and a strong inclination toward kindness and empathy. His design in this series features larger black eyes compared to other interpretations, aligning with the anime's visual style while maintaining his recognizable white, rounded troll-like appearance with a prominent snout.

His background as part of the Moomin family remains consistent with Tove Jansson's original creation: he is the son of Moominmamma and Moominpappa, residing in Moominvalley. The family dynamic emphasizes warmth, inclusivity, and a bohemian lifestyle, often welcoming diverse characters. Moomin's relationships are central; he shares a deep bond with his best friend Snufkin, whose return in "Snufkin's Back" highlights Moomin's loyalty and joy. He maintains a close, protective connection with Snorkmaiden and Little My, the latter informally adopted into the family.

His personality emerges through episodic adventures focusing on his emotional responses. In "Who's Afraid of Wolf?", Moomin confronts fear and misunderstanding, showcasing innate bravery despite initial apprehension. In "The House of Meso-Meso", he demonstrates compassion by supporting Sorry-oo. His interactions with Too-Ticky, who first appears in this anime, illustrate his receptiveness to wisdom and practical guidance during uncertainty.

The series occasionally delves into Moomin's introspection, particularly in "Lonely Winter", where he navigates solitude and seasonal changes, reflecting adaptability and resilience. His community role is evident in stories like "The Police Inspector is Gone", where he participates in collective efforts to address disruptions, reinforcing his cooperative nature.

While the anime introduces original scenarios, Moomin's core traits—curiosity, kindness, and commitment to friendship—remain anchored in his literary origins. His development culminates in themes of transition and acceptance, seen in the finale "Farewell, Moomin Valley".