ABSTRACT Flaky Cu (f-Cu) particles with surface modification by polystyrene (PS) coating layer were incorporated into poly(vinylidene fluoride) (PVDF), to obtain high dielectric constant (k) and thermal conductivity (TC) but low dielectric loss polymer composites. The results confirm the formation of a layer PS shell outside of the f-Cu, and indicate that the PVDF composites with f-Cu@PS particles exhibit superior dielectric properties compared with pristine f-Cu/PVDF. The improved dielectric performance can be attributed to the insulating PS interlayer preventing the f-Cu from direct contact with each other and meanwhile hindering the long-range electron migration. The dielectric properties of composites can be tuned through finely tailoring the PS shell’ thickness. Additionally, the f-Cu@PS/PVDF composites display slightly higher TC than the raw f-Cu/PVDF, owing to the suppressed thermal interfacial resistance and improved interfacial compatibility between the fillers and matrix. The obtained f-Cu@PS/PVDF composites with enhanced high-k and TC but low loss are promising materials for potential applications in microelectronic and electrical industries.