The aim of this study was to determine the effects of microwave pretreatment on physicochemical characteristics of carob flour and rice starch-based nanofibers produced by electrospinning. The effects of microwave heating on production of nanofibers by electrospinning have not been studied before. Another aim of the study was to fabricate and characterize nanofibers by using different carob flour concentrations (3%, 5% w/v) and rice starch (0.5% w/v). Films were characterized by scanning electron microscopy, water vapor permeability, X-ray diffraction, mechanical test, differential scanning calorimeter, and Fourier transform infrared spectrophotometer. Homogenous and bead-free fibers were obtained when microwave heating was used. Nanofibers originated from microwave-heated solution presented better characteristics in terms of water vapor permeability and mechanical properties as compared with conventionally heated ones. Microwave-heated solution had higher viscosity and available amino group amount as compared with conventionally heated solution. This study showed that microwave heating can be considered as a promising pretreatment method for electrospinning rather than conventional heating to be used in food packaging area.