Background: Minimally invasive dentistry increasingly seeks alternatives to conventional surgical and antimicrobial-intensive therapies. Photodynamic therapy (PDT) provides targeted antimicrobial and cytotoxic effects through the activation of a photosensitizer by light in the presence of oxygen, offering a selective and conservative therapeutic approach. Aim: To review the mechanisms of action, clinical applications, current evidence, challenges, and future directions of photodynamic therapy in modern dental practice. Methods: A narrative synthesis of recent experimental, clinical, and review literature was conducted. The review focused on PDT mechanisms, commonly used photosensitizers and light delivery systems, clinical outcomes across dental specialties, and emerging technological developments aimed at improving therapeutic performance. Results: Photodynamic therapy demonstrates strong antimicrobial efficacy, effective biofilm disruption, and selective tissue action without inducing microbial resistance. Clinical evidence supports its use as an adjunctive therapy in periodontology, endodontics, peri-implant therapy, caries management, oral infections, and early oral malignancies. PDT is associated with a favorable safety profile and minimal invasiveness. However, variability in treatment protocols, differences in photosensitizer properties, limited light penetration, and cost considerations contribute to inconsistent clinical outcomes. Conclusions: Photodynamic therapy represents a valuable adjunct in minimally invasive dentistry, offering targeted therapeutic benefits across multiple clinical applications. Despite promising evidence, barriers to routine clinical adoption remain. Ongoing advances in photosensitizer design, nanotechnology-based delivery systems, and light technologies are expected to enhance standardization, clinical effectiveness, and wider implementation.