The study evaluated the efficacy and safety of photodynamic therapy (PDT) combined with a recombinant mucin repair dressing in the treatment of post-inflammatory hyperpigmentation (PIH) in 310 patients with Fitzpatrick III-IV skin types. Patients underwent PDT according to wavelength and energy protocol, followed by immediate dressing application, with evaluation at 14 months. Combination therapy achieved greater pigment clearance at 4 weeks (42.3% vs. 25.6% in controls, p < 0.001), greater reduction in melanin density (31.5% vs. 17.2%, p = 0.021), and lower recurrence at 14 months (13.2% vs. 27.8%, p = 0.011). Adverse events included 5 toxic photoreactions (1.6%). Quality of life improved significantly (median DLQI score from 3.5 to 6.8, p < 0.001). The therapy provided better depigmentation, reduced recurrence, greater safety and better quality of life compared to standard treatment in darker skin types.