Background: Antimicrobial resistance (AMR) is a critical global health crisis exacerbated by persistent misuse and non-adherence to antibiotic therapies. Because comprehensive evidence detailing the specific factors driving these behaviors remains scarce, this systematic review aimed to identify and synthesize the multifactorial drivers influencing patient adherence and misuse across diverse populations. Method: Following the PRISMA guidelines, a systematic literature search was conducted to screen cross-sectional studies assessing antibiotic adherence, self-medication, and misuse. Eighteen studies met the inclusion criteria for final analysis. The methodological quality of the included studies was independently evaluated by two reviewers utilizing the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Analytical Cross-Sectional Studies. Result: The review identified complex factors across five domains: sociodemographic, knowledge and beliefs, medication-related, behavioral, and the health system. Lower education, younger age, and financial constraints consistently predicted non-adherence. Knowledge gaps were prevalent, particularly the misconception that antibiotics are effective for viral infections. Therapy-related factors, such as frequent dosing (e.g., three times daily) and long treatment durations, significantly reduced adherence. Behaviorally, premature discontinuation of therapy upon symptom relief was the most common form of non-adherence, leading to the retention of leftover antibiotics. Furthermore, health system factors, including easy access to non-prescription antibiotics and the lack of a regular doctor-patient relationship, facilitated inappropriate use. Conclusion: Patient adherence to antibiotics is influenced by a complex interplay of socioeconomic, cognitive, and structural factors. Effective interventions must be multifaceted, combining public education to correct misconceptions, prescriber-led simplification of treatment regimens, and stricter enforcement of dispensing regulations.