The influence of gold nanoparticles on electrohydrodynamic instabilities in polymer/nanoparticle nanocomposite thin films was studied as a function of nanoparticle concentration, electric field strength, molecular weight, and film geometry. Thin films of polystyrene mixed up to 1 vol % (20 wt %) of gold nanoparticles having polystyrene ligands under an applied electric field showed electrohydrodynamic instability patterns similar to those seen in pure polystyrene. The presence of gold nanoparticles increased the dielectric constant of the films, which led to a systematic reduction in the wavelength of the surface instabilities. Transmission electron microscopy showed that no migration or aggregation of the gold nanoparticles occurred as a result of the applied electric field. This work points to a simple route to reduce the size scale of columnar patterns generated by electrohydrodynamic instabilities.