Temporomandibular disorders (TMDs) are among the most common musculoskeletal conditions associated with chronic orofacial pain and functional disability. Chronic Myogenic TMD (MTMD) is the most prevalent subtype and is characterized by persistent masticatory muscle pain driven by peripheral and central sensitization mechanisms. Photobiomodulation (PBM) represents a conservative, non-invasive therapeutic modality within the medical management of TMD; however, the wavelength-dependent clinical and muscular effects remain inadequately defined. Aim: To compare the efficacy of three PBM wavelengths (635, 940, 1,064 nm) on pain intensity, mandibular function, surface electromyographic activity (sEMG), and pressure pain threshold (PPT) in patients with chronic myogenic TMD.