Background: Clear aligner therapy (CAT) offers aesthetic and hygienic advantages over traditional fixed orthodontic appliances. However, its uptake is influenced by patients' knowledge, attitudes, perceptions (KAP) and acceptance of the treatment. This study aimed to evaluate the KAP towards CAT among patients undergoing fixed orthodontic treatment and to identify demographic and socioeconomic factors influencing these attitudes. Methods: A cross-sectional survey was conducted at a private hospital in Lagos, Nigeria, involving all consenting follow-up orthodontic patients undergoing fixed appliance orthodontic therapy. A validated self-administered questionnaire assessed demographic characteristics and KAP toward CAT. Data were analysed using SPSS v26 and R software, employing chi-square and logistic regression. Results: Among 232 participants, only 50% had heard of CAT, and just 27.6% demonstrated good knowledge. About 52.2% showed a positive attitude, and 50.9% had a favourable perception. Significant associations were found between attitude and age (p = 0.022), education (p = 0.030), ethnicity (p = 0.035), and income (p = 0.013). Income uncertainty was a negative predictor of a favourable attitude (OR = 0.42, p = 0.025). Conclusion: Knowledge of CAT among patients treated with fixed appliances is limited, despite moderate awareness and positive attitudes. Educational and economic factors significantly influence acceptance. Improved education and affordability could enhance uptake of aligner therapy.