Bionanocomposites represent an emerging group of nanostructured hybrid materials. Besides the structural and functional properties similar to conventional nanocomposites, the inherent properties, namely, biocompatibility and biodegradability, make these environmentally benign materials highly attractive for both academia and industry. Research on bionanocomposites is an interdisciplinary field that is closely related to packaging and biological systems, such as tissue engineering and drug delivery, and also extended to electronics, sensor, and energy applications, just to name a few. This chapter will give an overview on the research progress of self-assembled bionanocomposites and artificial nanocomposites composed of typical biopolymers and nanoparticles, which exhibit dielectric functions and can have promising potential to be used in biological, electronic, and energy storage applications.