We present a new ternary semiconductor sensitizer-AgBiS2 for solar cells. AgBiS2 nanoparticles were grown using a two-stage successive ionic layer adsorption and reaction process. Post annealing transformed the double-layered structure into AgBiS2 nanoparticles of 16 nm in diameter. Liquid-junction semiconductor-sensitized solar cells were fabricated from the synthesized AgBiS2 semiconductor. The best cell exhibited a short-circuit current density Jsc of 7.61 mA/cm2, an open-circuit voltage of 0.18 V, a fill factor of 38.6%, and a power conversion efficiency η of 0.53% under 1 sun. The η increased to 0.76% at a reduced light intensity of 0.148 sun. The external quantum efficiency (EQE) spectrum covered the spectral range of 350–850 nm, with an average EQE of 54% over the main spectral region of 450–650 nm. The Jsc under 0.148 sun was equal to 1.69 mA/cm2, a respectable Jsc for a new sensitizer