A hybrid system of ZnO nanoparticles on multiwalled carbon nanotubes (MWNTs) is fabricated by simply heating Zn-coated MWNTs on a hot plate in air. Ultrafast optical switching and three-photon adsorption are observed from this hybrid system, and the absorption coefficient can be readily adjusted by changing the Zn-coating thickness. These results provide opportunities for cost-effectively integrating carbon nanotubes with functional oxide nanoparticles in future nanodevices.