In this study, the optimal parameters for the photodynamic inactivation (PDI) of Staphylococcus aureus in bacterial suspensions and in cheese were assessed using a water-soluble curcumin salt as the photosensitizer (PS). The in vitro study aimed at finding the optimal concentration and light dose to promote S. aureus photokilling. Four main groups were proposed: CONTROL (L−C−), LIGHT (L+C−), CUR (L−C+) and PDI (L+C+). A fixed light dose (LED, 450 ± 10 nm, 10 J cm⁻²) was applied using four different PS concentrations (0.75, 1.0, 1.5 and 3.0 mg mL⁻¹). The dose also varied from 10–100 J cm⁻² for a fixed concentration. High inactivation rates were observed for all light doses, with a maximum reduction of 7.58 log₁₀ at 100 J cm⁻² (p ≪ 0.05). Saturation of the PDI effect was observed after a 10 minute illumination time, as well as a slight decrease in the S. aureus population for increasing illumination times in the L+C− group. As an application, the concentration showing the best decontamination performance in vitro (0.75 mg mL⁻¹) was applied to decontaminate cheese in loco. PDI in two types of coalho cheese, a rennet-coagulated cheese commonly consumed in Brazil, was investigated. The results showed no significant inactivation in unpasteurized cheese, but a 4.34 log₁₀ reduction for t > 5 min in pasteurized specimens. In conclusion, the present PDI-catalyzed curcumin photosensitizer inactivated S. aureus at statistically significant levels in vitro, in pasteurized cheese, but not in unpasteurized specimens.