The three Sitwells siblings, all budding poets, introduced him to many major musical and literary figures of the time, including Delius, Diaghilev, and T. S. Eliot.

His chamber entertainment Façade of 1921 soon became popular as an orchestral suite and ballet.

The overture Portsmouth Point (1925) skyrocketed his international popularity, while the more introspective Viola Concerto (1929), premiered by Paul Hindemith, solidified his reputation in England and abroad.

Three major blockbusters followed: the monstrous choral work, Belshazzar's Feast (1931), the First Symphony (1935) for conductor Hamilton Harty, and a Violin Concerto (1939) commissioned by Jascha Heifetz.

The march Crown Imperial (1937), composed for the coronation of King George VI, placed him as Elgar's unofficial successor as master of the art of regalia.

Walton was by this time considered the foremost composer of Britain, and became a symbol of the hope that English music might recapture the brilliance it had in Handel's day.

During World War II, Walton primarily composed music for patriotic films, followed by the eight-year project Troilus and Cressida (1954), a tragic opera after the style of Puccini.

By then, Benjamin Britten had risen to the scene and taken Walton's place in the eyes of the critics, who reduced the latter to the rank of a stubborn reactionary who allegedly never captured the feel of contemporary music.

Nevertheless, Walton continued to compose in his own unique style, and some of his later output is quite remarkable, including an excellent Cello Concerto (1957) for Gregor Piatigorsky and commissions from the conductor Georg Szell (Partita for Orchestra, 1958), the Royal Philharmonic Society (Variations on a Theme of Hindemith, 1963), the Aldeburgh Festival (The Bear, 1967), and the cellist Mstislav Rostropovich (Passacaglia for Violoncello Solo, 1980).

During these later years of his life, Walton lived on the island of Ischia, near Naples.

He remained an active composer until his death there in 1983.