Bellany was born into the fishing community of Port Seton and studied at the Royal College of Art. He rejected what he saw as Edinburgh aestheticism and was inspired by the ideas of Hugh McDiarmid. In 1963-65 he and Sandy Moffat hung their canvases on the railings outside the RSA during the Edinburgh Festival, challenging the established Scottish Art World.
In 1965 he saw a Max Beckmann exhibition which had a lasting influence, as did a visit to Buchenwald in 1967. He produced a series of paintings based on the themes of original sin, sex, guilt and death, using a complex and personal system of symbols. Some, including fish, seagulls, skate and puffins were taken from his home whilst monkeys, skeletons and owls also featured. In the 1980s his health deteriorated and he had a liver transplant in 1988. During this period he painted a series of very personal portraits of family and doctors.
Bellany believed in national characteristics in painting and while he acknowledges the influence of French masters he strove to produced Scottish art. He had an enormous influence on a younger generation of Scottish artists including Peter Howson, Adrian Wisniewski and Stephen Campbell.