Adrian Ryan was born in Hampstead, London, and attended Eton College. He studied at the Slade School of Art from 1938 to 1940, where his contemporaries included Patrick Heron, Paul Feiler and Bryan Wynter. In 1943, he had had his first selling show at the Redfern Gallery, with the noted painter and collector Edward Le Bas among the early supporters of his work, as well as John Minton and Matthew Smith. His friends included many of the St Ives artists, especially Sven Berlin and Heron, but he did not share their interest in abstraction, and so chose to settle in Mousehole, in 1945, rather than in St Ives. There, he painted the local landscape in bold colours and expressive brushstrokes, reminiscent of the French Fauvists. Still Life was another subject of particular interest; for James Beechey, his depictions of oysters, crayfish and herrings "sometimes betray an unexpected undertone of disquiet". His oils were regularly selected for the Summer Exhibition at the Royal Academy, from where a painting of flowers was purchased for the Tate Gallery, in 1958.
His paintings won the respect of his peers, with Heron writing a number of positive reviews for The New Statesman. His work during the 1950s was included in several major survey exhibitions at the Tate, including Figures in their Setting (1953); The Seasons (1956); and The Religious Theme (1958). After returning to live in Mousehole (having lived in London during the '50s while teaching at Goldsmiths), Ryan was elected Chair of the Newlyn Society of Artists in 1962. He was part of the seminal exhibition St Ives 1939-64: Twenty-five years of painting, sculpture and pottery, held at the Tate in 1985.
Once described as "the best kept secret in the art world" by Francis Bacon, Ryan is represented in a number of major public collections, including the Government Art Collection, Tate, Manchester City Galleries and Penlee House Gallery.