Snufkin is a philosophical wanderer and adventurer who values simplicity, independence, and harmony with nature. He carries minimal possessions, lives in a green tent, and wears old green clothes with a wide-brimmed hat owned since birth. His few belongings include a harmonica used to compose melodies inspired by nature and emotional states, often blending expectation, spring sadness, and the joy of solitude. He occasionally plays other instruments like the flute, accordion, or guitar.

He is the son of the Mymble and the Joxter, making Little My and the Mymble's daughter his half-siblings. Snufkin first appears in Moominvalley during the events of *Comet in Moominland*, meeting Moomintroll and Sniff while playing his harmonica near a tent. This encounter establishes an immediate bond with Moomintroll, who introduces him as "one of the world’s wanderers." Their friendship is central; Snufkin returns to Moominvalley every spring after winter travels and departs each autumn. Reunions with Moomintroll at the valley’s bridge are recurring events, symbolizing their enduring connection despite Snufkin’s need for solitude.

Snufkin’s relationship with Moomintroll involves mutual respect but differing attachments. Moomintroll initially struggles with Snufkin’s departures, using a wish to send him food and rereading his letters for comfort. Over time, Moomintroll learns to appreciate solitude while continuing to hide his longing. Snufkin communicates through heartfelt letters left before each winter journey, promising to return "on the first warm spring day" and reassuring Moomintroll with phrases like "Cheerio." Their dynamic reflects Snufkin’s gentle handling of emotional bonds while maintaining independence.

He exhibits a strong aversion to authority, rules, and material ownership. He openly challenges figures like the Park Keeper, whose restrictive signs and fenced parks disrupt nature’s freedom. Snufkin removes prohibitive notices, encourages wild grass growth, and once planted Hattifatteners in a park to drive the keeper away. He believes possessions burden life, preferring memories over objects, and feels discomfort with new or clean items, such as rejecting new trousers for being "too new." His philosophical views emphasize personal freedom: "You can’t ever be really free if you admire somebody too much."

Despite his solitary nature, Snufkin assists others in need, such as temporarily fostering twenty-four lost woodies. He interacts warmly with Moominvalley’s residents, especially smaller or timid creatures who admire his quiet confidence. His wisdom and calm demeanor make him a trusted figure, often sharing insights during challenges. For example, he defines duty as "doing what you don’t want to" and advises that "the main thing in life is to know your own mind."

In broader adventures, Snufkin’s actions focus on restoring balance. He confronts disruptions like industrial parks overtaking Moominvalley, dismantling statues and signs while rallying other characters to help. His commitment to nature’s harmony drives these efforts, reflecting his core belief that unchecked authority sacrifices freedom for artificial order.

His character design evolved from initially appearing bald to later illustrations showing short, messy brown hair beneath his hat. This visual shift did not alter his essence as a symbol of serene rebellion and contemplative freedom.