Born and raised in Brussels, studied at and ran away from the Conservatoire, where his teacher Arthur De Greef had himself been a pupil of Liszt. His prodigious technique was further developed by a spell in the USA in the early 1920s. Shortly after returning to Europe he formed a musical partnership with the French pianist and composer Jean Wiéner, performing on two pianos at the Boeuf sur le Toit in Paris, where they played jazz, blues and hot dance, and in concert halls where they performed an even broader range of two-piano music including classical. They performed and toured together intermittently until 1939 when war broke out in Europe.
Between 1925 and 1937 they recorded around 100 sides of 78 rpm discs.
Doucet's monstrous talent and rigorous training enabled him to play impressive jazz and blues as well as dance and classical pieces. He was probably best known for Chopinata, a pot-pourri of Chopin pieces played in 2/4 time; he also recorded similar takes on Liszt, Wagner and Grieg. As a soloist he was an elegant and skilled accompanist to a number of leading French singers of the day. His accompaniment to Jean Renoir's silent film Charleston Parade (1927) was famous in its day but was never recorded.
After the second world war Wiener continued a musical career as a broadcaster and composer of film music, but Doucet, who had not wanted to be a musician anyway, never entered a studio again and returned to Brussels where he died in obscurity in 1950.