Bio-based polymers and their derivatives are promising green alternatives to petroleum-based polymers in the preparation of membranes. In this study, we developed microfiltration membranes based on acetylated cellulose ether (ACE), a high-molecular-weight cellulose-derived biopolymer, using vapor-induced phase separation. The properties of these membranes were analyzed and compared with those of a commercial cellulose acetate (CA) membrane. The pore sizes and pore distributions of the ACE membranes were controlled by the polyethylene glycol additives used in the preparation of the membranes. The ACE membranes with pore sizes of 0.20–0.53 μm were effective in removing Escherichia coli bacteria, demonstrating their viability in sterilization applications. The ACE membrane also exhibited high pure water permeance values (25,000 L m−2 h−1 bar−1) and lower non-specific protein binding compared to those of the commercial CA membrane. We believe that our study findings will promote the use of bio-based ACE membranes in commercial applications