Herein, we used chemical precipitation method to synthesize cadmium sulfide (CdS) nanoparticles (NPs) with different concentrations of CdNO3. The CdS NPs of size 105 nm and the corresponding zeta potential of 42.2 mV were achieved at CdNO3 concentration of 1 mM. X-ray diffraction (XRD) analysis revealed W-type hexagonal geometry of CdS NPs. The prepared CdS NPs were introduced into poly(hydroxybutyrate) (PHB) matrix to fabricate CdS/PHB composite nanomaterial. The physicochemical characterization showed successful synthesis of a novel nanocomposite. The XRD analysis showed that CdS/PHB nanocomposite exhibited hexagonal crystal structure, i.e., crystallite orientation of nanocomposite was majorly controlled by CdS NPs. Scanning electron micrographs of CdS NPs and CdS/PHB nanocomposite revealed spherical morphology of CdS NPs and their successful placement into PHB matrix with some random aggregations. The results were further confirmed using transmission electron microscopy (TEM) and a high-resolution TEM. Thermogravimetric analysis showed improved thermal characteristics of nanocomposites after incorporation of CdS NPs into PHB matrix.