A DSc from the University of Manchester followed in 1911, after which he served a short time at the Imperial College of Science and Technology as Senior Demonstrator in Chemistry.

Haworth organised the laboratories at St Andrews University for the production of chemicals and drugs for the British government during World War I (1914–1918).

[2] In 1933, working with the then Assistant Director of Research (later Sir) Edmund Hirst and a team led by post-doctoral student Maurice Stacey (who in 1956 rose to the same Mason Chair), having properly deduced the correct structure and optical-isomeric nature of vitamin C, Haworth reported the synthesis of the vitamin.

[6] Haworth had been given his initial reference sample of "water-soluble vitamin C" or "hexuronic acid" (the previous name for the compound as extracted from natural products) by Hungarian physiologist Albert Szent-Györgyi, who had codiscovered its vitamin properties along with Charles Glen King, and had more recently discovered that it could be extracted in bulk from Hungarian paprika.

During World War II, he was a member of the MAUD Committee which oversaw research on the British atomic bomb project.

In 1977 the Royal Mail issued a postage stamp (one of a series of four) featuring Haworth's achievement in synthesising vitamin C and his Nobel prize.