In this study, the surface chemistry and morphology and the photocatalytic and antibacterial potential of pure and chlorine (Cl)-doped indium sulfide (In₂S₃) thin films, produced by spray pyrolysis, were analyzed. The root-mean-square roughness seemed not to be affected significantly by the chlorine concentration in three of the doped films (around 12 nm). The roughness seemed not to affect the characteristics of the films analyzed in this study. The samples presented a photocatalytic efficiency higher than 80%, but no correlation with the chlorine concentration was found. The antibacterial potential of the films was assessed against the multidrug-resistant bacteria Pseudomonas aeruginosa, responsible for serious infections, which are extremely difficult to treat in hospitals. The obtained results evidence an increase in antibacterial activity with the increase in chlorine concentration. These results encourage further studies to support the potential of this material to be used in biomedical applications.