Complex permittivities of cadmium sulfide (CdS), zinc sulfide (ZnS), and of cadmium sulfide–zinc sulfide (CdS/ZnS) core–shell nanoparticles embedded in a polyvinyl alcohol matrix (PVA) were measured in liquid phase using a VectorNetwork Analyzer in the frequency range of 500 MHz–10 GHz. These nanocomposites are modeled as an embedded capacitor, and their electric field distribution and polarization have been studied using COMSOL Multiphysics software. By varying the thickness of the shell and the number of inclusions, the capacitance values were estimated. It was observed that CdS, ZnS and CdS/ZnS core–shell nanoparticles embedded in a polyvinyl alcohol matrix show capacitive behavior. There is a strong influence of the dielectric properties in the capacitive behavior of the embedded nanocapacitor. The capping matrix, position and filling factors of nanoinclusions all affect the capacitive behavior of the tested nanocomposites. Application of the CdS, ZnS and CdS/ZnS core–shell nanocomposite as the passive low-pass filter circuit has also been investigated. From the present study, it has been found that CdS/ZnS core–shell nanoparticles embedded in PVA matrix are potential structures for application as nanoelectronic filter components in different areas of communication.