We introduce a facile method to synthesize a new class of core-shell microspheres composed of resin core particles coated with various carbon materials. The core-shell microspheres were prepared by a one-pot process in which carbon materials such as edge-exfoliated graphite and expanded graphite were dispersed together with core substrates like polystyrene and poly(styrene/2-hydroxyethyl methacrylate) spherical particles in supercritical carbon dioxide. The obtained microspheres were characterized by thermogravimetric analysis, Raman spectroscopy, and scanning electron microscopy. The results indicate that the carbon shells are tightly attached to the surface of the core substrates. Furthermore, because of excellent adhesion, the carbon-coated polymer particles exhibited extremely high electrical conductivity with particle resistance of less than 50 Omega cm despite the presence of an insulating polymeric core material.