Graphene nanoplatelets with excellent electrical conductivity in polymer matrices are highly promising for the industrial application of electrical conductive materials, however, poor dispersion results in high contents of graphene nanoplatelets being required for electrical property enhancement. In this study, graphene nanoplatelets (GNP)@polyaniline (PANI) nanocomposites were synthesized by in situ polymerization whereas the compatibility between GNP@PANI nanocomposites and the polymer matrix improved significantly due to graphene nanoplatelet encapsulation with polyaniline. GNP@PANI nanocomposites were utilized to prepare a permanent antistatic high-density polyethylene (HDPE) composite through solution blending and press forming in order for GNP@PANI nanocomposites to be dispersed homogeneously in the HDPE. The dispersion and compatibility of GNP@PANI nanocomposites in the HDPE were verified by morphology characterization, resulting in significant improvement of the electrical properties of the GNP@PANI/HDPE composites. It was observed that surface resistivity (ρ_s) and volume resistivity (ρ_v) decreased sharply with a 10 wt% GNP@PANI addition of nanocomposites. The results displayed that in situ polymerization and solution blending were effective methods for a conductive network establishment by addition of only 2 wt% of GNP and 8 wt% of PANI.