Bionanocomposites with properties similar to those of conventional polymers derived from petroleum have shown scientific and industrial interest. The current research discuss the effect of graphite nanosheets (GNS) addition on electrical, electromagnetic, and mechanical properties and also on morphological aspects of the natural polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/GNS nanocomposites and neat PHBV prepared by casting method. Nanocomposite of PHBV/1.00 wt% GNS showed good electrical conductivity values, extending the scope of application of these materials, such as in reflectors. One of the objectives of this study was to investigate the effect of different contents of GNS in neat PHBV using dynamic mechanical analysis (DMA), which showed that the addition of GNS in PHBV matrix improved the DMA properties. Transmission electron microscopy (TEM) shows good dispersion of GNS in the PHBV matrix with stacked and intercalated graphite layers and XPS confirmed the presence of carbon and oxygen in the graphite nanosheets surface.