In 1945, Corbett was appointed as a lecturer in chemistry at Otago. After returning from Cambridge in 1950, Corbett rose to become a professor in 1966, and the Mellor Professor of Chemistry in 1972. When he retired in 1983, he was accorded the title of professor emeritus.
Corbetts research at Otago was primarily concerned with the study and structural elucidation of essential oils isolated from New Zealand native plants by steam distillation. Under his supervision in 1970, doctoral student Denis Lauren first isolated the diterpene compound from the rimu tree (Dacrydium cupressinum') that came to be known as laurenene. Corbett also investigated extractives from barks, leaves, heartwoods and lichens, and determined the structures of many new, and derivatives of known, di-, tri- and sesquiterpenoids. He also studied the synthesis and rearrangement of some of the compounds that his team isolated.