Born in 1944, Barry was of Caucasian and Māori descent. He grew up on farms in the Wairarapa, leaving at fifteen to begin studies for the Roman Catholic priesthood in Australia. He left after six years, returning to the Wairarapa where he worked for one year in radio before joining a Masterton-based rural film company as a cameraman.
Four years later he joined John O'Shea's Pacific Films as a director of trade films, television commercials and documentaries. His documentaries of that period include All That We Need, an energy conservation cinema documentary which opened the 1973 Tehran Film Festival; and Indira Ghandi, a 60 minute documentary profile of the Prime Minister shot in India in 1976 at the height of the Emergency.
Of significance was the landmark Tangata Whenua series of documentaries exploring Maori life and culture  on which he worked closely with the late Michael King. In the late 1970s and early 1980s, Barry was abroad and worked on projects in Sri Lanka, London, Paris and Amsterdam. He returned to New Zealand to write and direct The Neglected Miracle, a feature-length political documentary on the ownership of plant genetic resources, shot over two years in eight countries.
In 1987, Barry became the first Māori to direct a dramatic feature Ngāti, which won Best Film at the Taormina Film Festival, Italy. In 1991 Barry wrote and directed the feature Te Rua, a fictional story about a group of Māori who set off for Berlin to claim back tribal carvings held in a museum there. This was followed byThe Feathers of Peace, a feature drama-documentary based on the Moriori people of Rekohu (the Chatham Islands). Barry also turned his hand to writing. His book Mana Tuturu: Māori Treasures and Intellectual Property Rights, published by Auckland University Press was launched at the end of 2005.
In 2006, Barry was honoured at Dreamspeakers, the 11th Annual International Film Festival. The Honour recognises aboriginals in the film industry who have made significant contributions to promoting and protecting their culture and heritage.
Throughout his career Barry developed innovative approaches to filmmaking based on a deep respect for community values. He was a strong advocate for Māori spiritual and cultural rights. Fellow filmmaker, friend and 2001 Laureate Dame Gaylene Preston said “Barry Barclay was a true pioneer film-maker who established many important networks for encouraging Māori film-making. Māori stories by Māori, for Māori. He was a true visionary. He made films about his community and their concerns and he encouraged his community to make their own films”
Barry received an Arts Foundation Laureate Award in 2004 and was awarded a Member of the New Zealand Order of Merit for his services to film in 2007. He was posthumously awarded the inaugural Te Puni Kokiri Lifetime Achievement Award for Indigenous Television Broadcasting, Te Rerenga Tahi. The new award was launched as part of WITBC ’08 – a three-day gathering of indigenous television leaders from throughout the world which was hosted by New Zealand’s national indigenous broadcaster, Māori Television, at the end of March 2008.
Images of Dignity: Barry Barclay and Fourth Cinema written by Stuart Murray is a major study of Barry's films and draws parallels between his work and that of other indigenous filmmakers and activists.The book was released at the international Film Festival in Poland in July 2008. It is published by Huia Press.
Barry Barclay died on 18 February 2008, aged 63, following a stroke.