The main disadvantage of membrane bioreactor (MBR) technology, which is an important alternative for advanced wastewater treatment, is fouling. In this regard, polyether sulfone (PES) membranes were prepared by adding bismuth 2,3-dimercapto-1-propanol (BisBAL) chelate to the dope solution for biofouling control. BisBAL was synthesized using bismuth metal and a thiol. The bare and BisBAL-doped PES membranes were tested for their physical properties and biofouling resistance properties using xanthan gum solution as a model foulant and real activated sludge. The results showed that the BisBAL-doped PES membrane has a lower absorptive surface and fouling tendency when compared to the bare PES membrane. Bismuth release from BisBAL-doped PES membrane during pure water filtration was measured using inductive-coupled plasma spectrometry and the results showed that bismuth release from BisBAL-doped PES membrane was quite low. According to the MBR operation results, it can be said that the rate of transmembrane pressure increase, total fouling and biofilm creation could be decreased with BisBAL-doped PES membrane usage without any effect on activated sludge structure and microbial community population in the MBR. BisBAL-doped PES membranes did not lose their durability and anti-biofouling activities in time and could be chemically washed. The novelty of this study was the application of a microfiltration membrane manufactured with bismuth metal in MBR operation.