In this study, the morphological, electrical, and rheological properties of the poly(propylene carbonate) (PPC)/poly(lactic acid) (PLA)/multi-walled carbon nanotube (MWCNT) composites were investigated. From the results of transmission electron microscopy of the PPC/PLA/MWCNT composites, the MWCNT preferred to locate more in the PPC phase than in the PLA phase. This maybe due to the lower interfacial tension of the PPC/MWCNT composites compared to that of the PLA/MWCNT composites. The electrical conductivities of the PPC/PLA/MWCNT composites were higher than those of the PPC/MWCNT and the PLA/MWCNT composites, which was likely due to the selective localization of the MWCNT in the PPC phase (continuous phase). From the results of the complex viscosity of the composites, the ratio of increasing the complex viscosity of the PPC/MWCNT composites with the MWCNT content was higher than that of the PLA/MWCNT composites. This is maybe due to the fact that the MWCNT dispersion in the PPC phase was higher than in the PLA phase. The results from the morphology, electrical conductivity, and complex viscosity of the PPC/PLA/MWCNT composites suggest that the selective localization of the MWCNT in the PPC phase can improve the conductive path and increase the electrical conductivity of the PPC/PLA/MWCNT composites.