The synthesis, characterization, and antimicrobial properties of functionalized copper nanoparticle/polymer composites are reported. Copper nanoparticles (Cu NPs) are stabilized by surface attachment of the acrylic functionality that can be copolymerized with other acrylic monomers, thus, becoming an integral part of the polymer backbone. Biological experiments show that Cu NP/polymer composites exhibit antimicrobial activity similar to that of conventional copper-based biocides. Atomic absorption spectroscopy shows the smallest amount of copper ions leaching from chemically bound acrylated Cu NPs compared to the nonfunctionalized biocides. These composites have a strong potential for use in antibacterial or marine antifouling coatings.