Peter Reginald Kelly was born at Skidegate, British Columbia on April 21, 1885. He was a member of the Haida.

Peter studied theology at Coqualeetza Institute and Columbia College, both Methodist institutions. He taught school for five years at Skidegate, British Columbia before becoming a lay preacher. Later, he became an ordained minister and served in several pastorates and as captain of the Thomas Crosby III and Thomas Crosby IV mission ships.

Peter was an advocate for Indigenous rights, particularly surrounding BC land claims. As president of the Allied Tribes of BC (ATBC), he testified on Indigenous grievances before a special parliamentary committee in 1927. He was active in the Native Brotherhood of BC in the 1930s and he was a key figure in the consultations of the late 1940s that led to a revision of the Indian Act.

In 1948, Kelly received an honorary degree in theology from the University of British Columbia. In 1957, he was elected president of the Conference of the United Church in British Columbia.

Peter Reginald Kelly died at Nanaimo, British Columbia on March 2, 1966.