It was as a fellow of St. John’s College, Cambridge (1884–96), that Stout published his first work in 1896: the two-volume Analytic Psychology, whose view of the role of activity in intellectual processes was later verified experimentally by the Swiss psychologist Jean Piaget. Stout was appointed to a new lectureship in Comparative Psychology at the University of Aberdeen in 1896, before becoming reader in mental philosophy at the University of Oxford (1898–1902), where he published his Manual of Psychology in 1899. This work formulated many principles later developed experimentally by the Gestalt school of psychology. Leaving Oxford, from 1903 to 1936, Stout served as professor of logic and metaphysics at St. Andrews, Fife, where he published another major work, Mind and Matter in 1931. He remained at St. Andrews until his retirement thirty years later, in 1936.
Upon his retirement, George Frederick Stout left for Australia to be with his son. He died in Sydney in 1944.
Over the course of his career, Stout taught a number of notable students, including G. E. Moore and Bertrand Russell at Cambridge University. In addition, from 1891 to 1920, he served as editor of Mind, a leading philosophical journal, and was president of Aristotelian Society from 1899 to 1904.