Ternary semiconductor nanocrystals from the I–V–VI family have potential applications in many fields. In this work, we report on the synthesis of well-dispersed Cu₃SbS₃ nanocrystals with an average diameter of 23.0 ± 4.9 nm. The as-synthesized Cu₃SbS₃ nanocrystals are of high phase purity and stable against phase separation when heating up to 400 °C in an inert atmosphere or left at room atmosphere for 80 days. The optical band gap of the nanocrystals is calculated as ~1.87 eV. The nanocrystal film shows strong near infrared absorption and is sensitive towards detecting trace amounts of Rhodamine 6G by using surface-enhanced Raman scattering. These observations imply the huge potentials of Cu₃SbS₃ nanocrystals in photothermal, photovoltaic, and sensing applications.