We synthesized and evaluated a novel class of chelator-free [Cu-64]CuS nanoparticles (NPs) suitable both for PET imaging and as photothermal coupling agents for photothermal ablation. These [Cu-64]CuS NPs are simple to make, possess excellent stability, and allow robust noninvasive micro-PET imaging. Furthermore, the CuS NPs display strong absorption in the near-infrared (NIR) region (peak at 930 nm); passive targeting prefers the tumor site, and mediated ablation of U87 tumor cells occurs upon exposure to NIR light both in vitro and in vivo after either intratumoral or intravenous injection. The combination of small diameter (similar to 11 nm), strong NIR absorption, and integration of Cu-64 as a structural component makes these [Cu-64]CuS NPs ideally suited for multifunctional molecular imaging and therapy.