Membrane biofouling remains a significant challenge in the application of ultrafiltration (UF) pretreatment systems in desalination and water industries. Bacterial biofilms produce extracellular polymeric substances, which contain alginate as a major component. There has been an ongoing search to look for passive/non-chemical means of mitigating this problem. We present a method based on immobilization of a polysaccharide-degrading enzyme, alginate lyase (Alg L), onto cellulose acetate membrane to control biofilm formation. Various parameters like Alg L concentration, cross-linker concentration and pH were optimized. Two immobilization procedures were adopted and the Alg L immobilization efficiency of each method was compared. Activation of membrane with a cross-linking agent, followed by Alg L immobilization was found to be relatively more effective. Immobilization was confirmed by determining the activity of the immobilized enzyme; viscosity decrease corresponding to enzymatic degradation of the substrate was observed. The immobilization protocol was found to be highly reproducible. The ability of the test membrane to mitigate Pseudomonas aeruginosa biofilm formation was confirmed by scanning electron microscopy. The results show that Alg L immobilization on UF membrane can be used for controlling polysaccharide fouling on membrane filters used in advanced water purification techniques.