The principle of breathable food packaging is to provide the optimal number of pores to transfer a sufficient amount of fresh air into the packaging headspace. In this work, antimicrobial microporous eco-friendly polymeric membranes were developed for food packaging. Polylactic acid (PLA) and polycaprolactone (PCL) were chosen as the main packaging polymers for their biodegradability. To develop the microporous films, sodium chloride (NaCl) and polyethylene oxide (PEO) were used as porogenic agents and the membranes were prepared using solvent-casting techniques. The results showed that films with of 50% NaCl and 10% PEO by mass achieved the highest air permeability and oxygen transmission rate (O2TR) with PLA. Meanwhile, blends of 20% PLA and 80% PCL by mass showed the highest air permeability and O2TR at 100% NaCl composition. The microporous membranes were also coated with cinnamaldehyde, a natural antimicrobial ingredient, to avoid the transportation of pathogens through the membranes into the packaged foods. In vitro analysis showed that the biodegradable membranes were not only environmentally friendly but also allowed for maximum food protection through the transportation of sterile fresh air, making them ideal for food packaging applications.