Born in 1936, Don Selwyn grew up in Taumarunui. Originally a rugby-playing English teacher, his acting career was initiated by a dare: he attended a rehearsal of Shakespeare's A Midsummer Night's Dream with a friend who was acting in the production and when the actor playing Oberon became ill, the director, Nola Millar, asked Selwyn to take over the role. He made his theatrical debut in a pink tutu with butterfly wings, to the amusement of his rugby mates.
Selwyn was a founding member of the New Zealand Māori Theatre Trust. From 1984 to 1990 he ran the film and television course He Taonga i Tawhiti (Gifts from Afar), providing Māori and Pacific Islands people with the technical skills to tell their own stories in film and television. With producer Ruth Kaupua Panapa, he formed He Taonga Films in 1992 to create job opportunities for course graduates and to provide outlets for Māori drama writers. Selwyn also produced and directed Māori language dramas Māui Potiki, Tohunga and several Māori dramas in English, including Don't Walk With Your Nose in the Air (awarded Best Foreign Short Film at New York Film Festival 1992). He was Executive Producer of the 2000 New Zealand Media Peace award-winning feature The Feathers of Peace, as well as producing the film Te Tangata Whai Rawa o Weniti, the Māori Merchant of Venice. He was also appointed Adjunct Professor of Te Whare Wananga O Awanuiarangi.
His awards and recognitions include the Officer of the Order of New Zealand Merit (ONZM) 1999, an Honorary Doctorate of Literature from Massey University, an honorary performing arts degree from Unitec and Te Tohu Tiketike a Te Waka Toi, an award presented annually by Te Waka Toi for outstanding contribution to the development of Māori arts.