This study evaluates the impact of Clinical Decision Support Systems (CDSS) on reducing medication errors and enhancing patient safety in a tertiary hospital. A mixed-methods approach was employed, including a retrospective analysis of medication error rates and qualitative insights from pharmacists and health informaticians. Quantitative findings revealed a 50% reduction in total medication errors post-CDSS implementation, with significant decreases in drug-drug interaction and allergy-related errors. Qualitative analysis highlighted themes such as improved patient safety, enhanced workflow efficiency, and challenges like alert fatigue and technical barriers. Collaboration between pharmacists and health informaticians emerged as a key factor in optimizing CDSS utility. Recommendations include tailoring alerts, ongoing training, and robust system design to address identified challenges. These findings underscore the potential of CDSS in improving medication safety and healthcare delivery in tertiary hospital settings.