As an assistant to The Svedberg at the University of Uppsala (1925–32), Tiselius developed the use of electrophoresis for the delicate task of separating proteins (protein) in suspension on the basis of their electrical charge. For this work he was awarded his doctorate in 1930.

After lecturing at Uppsala, he conducted research at the Institute for Advanced Study at Princeton (1934–35). Returning to Uppsala (1937), he became a professor of biochemistry and was provided with a newly built institute to house his department. He used electrophoretic methods to separate the chemically similar proteins of blood serum, an achievement that was especially cited in the Nobel award. In 1940 he began research into the separation of proteins and other substances by adsorption chromatography. Tiselius was chairman of the Swedish Natural Science Research Council (1946–50) and then became vice president (1947–60) and president (1960–64) of the Nobel Foundation.