Soy protein (and associated carbohydrate) (SOY) is graft copolymerized with poly(methyl methacrylate) (PMMA) to synthesize novel low cost dielectric materials for multifunctional applications. Graft copolymerization of methyl methacrylate onto pre-activated SOY is carried out using a simple reflux method to form covalently bonded PMMA-g-SOY copolymers. The resulting PMMA-g-SOY is processed into films without employing any toxic chemical solvents. The PMMA-g-SOY films exhibited enhanced storage modulus and a low loss tangent together with promising dielectric properties compared to the pristine PMMA polymer. This strategy may open a new avenue to efficiently use green co-products for multifunctional applications in traditional and structural capacitors.