Worm-Müller became dr.philos. in 1919 with the thesis "Norge gjennom nødsaarene", a documentation on the period from 1807 to 1810. He referred to this period as the "distress years" since Norway suffered from the Gunboat War and the Continental System. He started lecturing at the University of Kristiania in 1919, and was a professor from 1928. His research work "Christiania og krisen efter Napoleonskrigene" from 1922 is regarded a central contribution to economic history. He was editor-in-chief for the magazine "Samtiden" from 1925 to 1940, and again from 1945 to 1963. He was delegate to the League of Nations in 1926 and 1927. He participated in politics during the 1930s, by running for election to the Norwegian Parliament for the Liberal Party, but was not elected.