Jan van Os was born in Middelharnis. He was taught by the animal, still life and decorative painter Aert Schouman (1710–1792) in The Hague, and joined the painters’ confraternity in 1773.
Van Os spent the rest of his life in The Hague, although he enjoyed an international reputation and exhibited paintings in London, France, and Germany.
He painted mainly fruit and flower pieces, in the tradition of Jan van Huysum, and also a few landscapes and seascapes. Three of his children were also painters: Georgius Jacobus Johannes van Os, Maria Margaretha van Os, and Pieter Gerardus van Os.