Background: Adult orthodontic demand in Saudi Arabia is increasingly shaped by aesthetic visibility, professional schedules, digital expectations, and willingness to invest in comfort. Clear aligners and fixed appliances now compete for the same adult population, yet their comparative value is not explained by esthetics alone. Aim: This review evaluates comparative outcomes of clear aligners and fixed orthodontic appliances in adult Saudi patients, with attention to treatment effectiveness, treatment duration, pain, oral health-related quality of life, periodontal impact, patient satisfaction, and case selection. Methods: A structured narrative review was designed for evidence published between 2020 and 2025. Eligible sources included randomized trials, prospective studies, cross-sectional Saudi studies, and recent evidence syntheses that compared clear aligners with fixed appliances or examined patient-reported outcomes relevant to adult orthodontics. Findings were mapped to a Saudi clinical context by considering adult expectations, oral hygiene behaviour, access to specialist follow-up, compliance demands, and cost sensitivity. Results: Current evidence suggests that aligners provide better early comfort, lower short-term interference with daily life, superior aesthetic acceptability, and easier hygiene during active treatment. Fixed appliances remain more efficient and mechanically dependable for complex movements, severe crowding, extractions, anchorage-demanding cases, and low-compliance patients. In adult Saudi practice, the most defensible conclusion is not appliance superiority but targeted selection: aligners suit motivated adults with mild to moderate malocclusion and strong cosmetic priorities, whereas fixed appliances suit complex malocclusion, uncertain compliance, and treatment plans where precise three-dimensional control is critical. Conclusion: A shared decision model integrating clinical complexity and patient-centred outcomes is necessary for adult Saudi orthodontic care.