Pharmacovigilance represents a critical component of public health systems worldwide, serving as the scientific discipline dedicated to the detection, assessment, understanding, and prevention of adverse effects and other drug-related problems throughout the entire product lifecycle. The importance of robust pharmacovigilance systems has been underscored by numerous drug safety crises that have emerged during post-marketing surveillance, highlighting the limitations of pre-approval clinical trials in detecting rare or delayed adverse events. This article aims to provide a comprehensive overview of the role of pharmacovigilance in drug safety monitoring, examining its fundamental principles, methodologies, and evolving practices. Key components discussed include spontaneous adverse drug reaction reporting systems, active surveillance mechanisms, signal detection methodologies employing statistical and data mining techniques, risk assessment frameworks, and the implementation of risk management strategies including Risk Evaluation and Mitigation Strategies. The article further explores regulatory oversight mechanisms, international collaboration through organizations such as the World Health Organization Programme for International Drug Monitoring, and the impact of pharmacovigilance activities on regulatory decision-making processes including label modifications, restricted indications, and market withdrawals. Emerging trends including the integration of real-world evidence, artificial intelligence applications, and patient-reported outcomes are examined as transformative approaches to proactive safety monitoring. The future outlook emphasizes the transition toward predictive pharmacovigilance models that leverage big data analytics, electronic health records, and genomic information to enable personalized risk assessment and enhance patient safety on a global scale.