The extensive adoption of dental implants has greatly enhanced the functional and aesthetic rehabilitation of patients who are partially or completely edentulous. Nevertheless, the rising incidence of peri-implant diseases has become a significant clinical issue in the field of implant dentistry. Peri-implant mucositis and peri-implantitis are inflammatory disorders triggered by the accumulation of biofilm around dental implants, characterized by the progressive destruction of peri-implant tissues if not addressed. Traditional treatment methods, including mechanical debridement, antiseptic agents, and supplementary antibiotic therapy, frequently exhibit limited effectiveness due to the intricate surface morphology of implants and the resilience of dysbiotic biofilms. Antibacterial photodynamic therapy (aPDT) has been introduced as a non-invasive adjunctive treatment option that employs a photosensitizer activated by light of a specific wavelength to produce reactive oxygen species capable of selectively eliminating pathogenic microorganisms. Recent developments, particularly dual-light antibacterial photodynamic therapy that combines blue light and near-infrared light, have shown improved antimicrobial effectiveness and a notable decrease in inflammatory biomarkers. This review discusses the pathogenesis of peri-implant diseases, the limitations of conventional treatment approaches, the biological principles underlying aPDT, and the clinical evidence that supports the use of dual-light photodynamic therapy in the management and preservation of peri-implant health.