Deakins was born in Torquay in the English county of Devon, the son of Josephine (née Messum), an actress, and William Albert Deakins, a builder. He attended Torquay Boys' Grammar School. While growing up in Torquay in adolescence, Deakins spent most of his time in and out of school focusing on his primary interest: painting. Several years later he enrolled in the Bath School of Art and Design (in the city of Bath) where he studied graphic design. While studying in Bath, he discovered his love of photography. As it turned out, he was a very talented photographer, and this led him to be hired to create a photographic documentary of his hometown, Torquay. About a year or so later, Deakins transferred to the National Film and Television School in Buckinghamshire.
Shortly after graduating, Deakins found work as a cameraman, assisting in the production of documentaries in various locations abroad for approximately seven years. During this seven-year stint, his first project involved a nine-month trip as one of the entrants of a 'round-the-world yacht race called, Around the World With Ridgeway. This project captured the lives and growing tensions between several of the yacht's crewmen. Deakins received high praise for his work out at sea showing the parallels between these teammates and shipmates. After completing Around the World With Ridgeway, Deakins was immediately hired by television studios to film several documentaries in Africa. His first, Zimbabwe, was a powerful and informative depiction of the genocide that had been going on there, following Zimbabwe's devastating civil war. His second African documentary, Eritrea – Behind Enemy Lines, was another depiction of conflict, this time within the borders of Sudan, Ethiopia and Djibouti.
Deakins married script supervisor Isabella James Purefoy Ellis, professionally known as James Ellis, on 11 December 1991. Deakins' primary hobby is taking still photographs. Before he entered the National Film School, he spent a year in North Devon, England, documenting the way of life on the farms and in the villages. This cemented his passion for still photography that continues to this day. On the rare days that he is not in his boat while in Devon, he enjoys travelling to various places to augment his growing series of images.