Silver antimony sulfide (AgSbS2) has attracted great interest as a photovoltaic absorber, attributed to its suitable energy gap, large absorption coefficient, and being of relatively earth‐abundant elements. However, the applications of AgSbS2 are very limited due to the immaturity of the fabrication technology. A novel spray pyrolysis method for AgSbS2 film deposition is reported. Selenization is the most important step to improve the device performance. The composition analysis shows that the S element in AgSbS2 can be partly substituted by Se via heating the sample in Se vapor at 400 °C for several minutes. X‐ray diffraction shows that the selenized film contains AgSbS2, AgSbSe2, and AgSbS2−xSex without other impurities. The Hall effect confirms a carrier concentration of 3.31 × 1018 cm−3, which is significantly higher than that of the untreated film and those processed in other atmospheres. The optical measurement indicates that the optical absorbance of the selenized AgSbS2 is tremendously improved. In addition, a cascade‐type energy level with the bandgap varying from 1.15 eV at the surface to 1.68 eV into the bulk is formed, resulting in an ideal energy level matching. Because of these beneficial factors, the efficiency improves significantly from 0.27% to 1.30%.