Ligand fishing is a convenient bioanalytical screening method that is based on the affinity selection of a ligand from a complex biological sample by an immobilized receptor. It is a versatile affinity-based screening approach and it has found application in multiple interacting pairs such as enzyme-inhibitor/activator, antigen-antibody, receptor-ligand, and protein-protein. Important parameters that affect the successful operation of the method are the high specificity and strong binding affinity of the interacting pair (e.g., enzyme-ligand complex) and the elution of the bound ligand from the complex. This chapter provides protocols for the synthesis of affinity adsorbent and its application in off-line ligand-fishing procedure for a 6His-tagged glutathione transferase (GST).