The maintenance of international peace and security remains one of the most pressing challenges of the contemporary global order. The United Nations was established in the aftermath of the Second World War with the primary objective of preventing armed conflict, promoting collective security, and fostering international cooperation among sovereign states. At the center of this mandate lies the United Nations Security Council, which is entrusted with the responsibility of identifying threats to peace, responding to breaches of peace, and addressing acts of aggression through diplomatic, economic, and, when necessary, military measures. Alongside the Security Council, various United Nations agencies and peacekeeping mechanisms perform a complementary role in conflict prevention, humanitarian assistance, peace building, and post-conflict reconstruction. These agencies contribute by addressing the root causes of conflict, such as poverty, displacement, human rights violations, and underdevelopment, thereby reinforcing the broader objectives of global peace and stability. This research paper critically examines the role, challenges, and effectiveness of the United Nations Security Council and its associated agencies in maintaining international peace. It analyzes the institutional framework and legal authority of the Security Council, while also highlighting key political constraints that limit its effectiveness, particularly the use of veto power by permanent members. The study further evaluates the Council’s performance in responding to contemporary security challenges, including civil wars, terrorism, humanitarian crises, and emerging non-traditional threats. The paper concludes that while the Security Council and UN agencies have made significant contributions to global peace, structural limitations and geopolitical rivalries continue to undermine their overall effectiveness, emphasizing the need for meaningful reforms and stronger multilateral cooperation.