A process of forming a gluten-derived flame retardant material includes forming an amine-functionalized flame retardant molecule that includes an aryl halide group and a phosphorus moiety. The process also includes chemically reacting the amine-functionalized flame retardant molecule with a gluten protein under transamidation conditions to bind the phosphorus moiety to a first portion of the gluten protein. The process further includes initiating a cross-coupling reaction between the aryl halide group and amine group of a second portion of the gluten protein to form a gluten-derived flame retardant material.