Trained as a philologist, Huysmans taught at the collège at Ieper, Belg., the Athenaeum at Ixelles, Belg., and the Université Nouvelle (French: “New University”) in Brussels. From 1910 he served in the House of Representatives, first for Brussels and then for Antwerp, acting as secretary for the Second International based in Brussels (1905–22). In the years before World War I he wrote for several socialist newspapers, including Le Peuple, and after the war started the Flemish Volksgazet in Antwerp, where he helped form a Socialist Party branch and became the city's mayor (1933).

As minister of education (1925–27), Huysmans promoted teaching in Flemish in the Flemish provinces. After serving as president of the House of Representatives (1936–39), he fled the Nazi occupation (1940) to London, where he became vice chairman of the Belgian Parliamentary Consultative Committee. After the war he led a coalition ministry (1946–47) and served as minister of education (1947–49) in the succeeding ministry of Paul-Henri Spaak.

Huysman's writings include Soixante-quinze années de domination bourgeoise (1905; “Seventy-Five Years of Bourgeois Domination”), La Révolution de 1830 et le mouvement politique (1905), L'Affiliation des syndicats (1907; “The Consolidation of the Trade Unions”), Études sur les assurances sociales (1913; “Studies on Social Insurance”), and Quatre Types (1937; “Four Models”).