Significance Direct measurement of protein diffusion at a solid–liquid interface, unlike that in a bulk liquid phase, is challenging, particularly in complex adsorbent geometries. As a result there is disagreement as to whether surface diffusion contributes significantly to protein transport into porous ion-exchange chromatography (IEX) beads. We provide complementary evidence supporting the role of surface diffusion in protein transport into IEX media and show that the diffusivity depends explicitly on adsorption affinity. Exploiting this relationship, we further present an innovative procedure for loading protein onto a column that increases the column productivity by 43% for purification of a monoclonal antibody. We therefore provide a multipronged approach for investigating protein surface diffusion and validate its significance in protein transport.