Polyethersulfone (PES) is a widely used polymeric material for ultrafiltration or nanofiltration membranes. To enhance membrane permeability, rejection, and antifouling performance, the effect of four different types of carbon-based nanomaterials and air exposures during PES/carbon-based nanomaterial membrane fabrication was evaluated. The carbon-based nanomaterials were pristine carbon nanotubes, oxidized CNTs (CNTs-O), pristine graphene nanoplatelets (GNPs-P), and oxidized graphene nanoplatelets (GNPs-O). The characteristics and performances of pure and blended membranes were investigated based on their permeability, porosity, morphology, and hydrophobicity. Longer air contact time during membrane preparation resulted in lower membrane permeability, hydrophobicity, and porosity. All fabricated membranes tended to have channelled sponge-like structure, and highest permeability was attributed to the PES/GNPs-O membrane.