Corruption is a global problem that undermines democracy, worsens inequality, and erodes governance. Among its forms, grand corruption—when high-level authorities misuse power for narrow interests—causes the most severe damage by weakening institutions and harming public trust. This article reviews literature and case studies, showing how grand corruption links to extremism. When citizens perceive systemic injustice, they are more likely to lose confidence in government and become vulnerable to radical ideologies. Extremist groups exploit dissatisfaction with corruption to recruit members, justify violence, and gain public sympathy. Recent events in Indonesia, Nepal, and the Philippines illustrate how structural abuse of power can fuel riots, social unrest, and extremist mobilization. Addressing grand corruption is therefore not only a matter of financial integrity or governance reform, but also a crucial step toward strengthening democracy, protecting human rights, and enhancing both national and international security against extremist threats.