The goal of this study was to develop near-infrared (NIR) resonant gold-gold sulfide nanoparticles (GGS-NPs) as dual contrast and therapeutic agents for cancer management via multiphoton microscopy followed by higher intensity photoablation. We demonstrate that GGS-NPs exposed to a pulsed, NIR laser exhibit two-photon induced photoluminescence that can be utilized to visualize cancerous cells in vitro. When conjugated with anti-HER2 antibodies, these nanoparticles specifically bind SK-BR-3 breast carcinoma cells that over-express the HER2 receptor, enabling the cells to be imaged via multiphoton microscopy with an incident laser power of 1 mW. Higher excitation power (50 mW) could be employed to induce thermal damage to the cancerous cells, producing extensive membrane blebbing within seconds leading to cell death. GGS-NPs are ideal multifunctional agents for cancer management because they offer the ability to pinpoint precise treatment sites and perform subsequent thermal ablation in a single setting.