<p>The rise of transnational crime has been a growing threat to international security and global governance. Transnational crime poses an even greater peril to developing countries and conflict-affected states, such as Afghanistan. Indeed, an epidemic of transnational crime has plagued Afghanistan over the last two decades. These crimes have been highly prevalent and many have occurred at large scale, especially drug trafficking, corruption, terrorism, and money laundering. These crimes have affected every aspect of life in the country. The U.S. and the international community poured billions of dollars into fighting terrorism, securing peace, and rebuilding Afghanistan for twenty years (2001–2021). Although international aid and efforts supported real progress in the country, they failed to achieve the ultimate goal of creating a peaceful and prosperous country with a fully functioning and stable government. While many factors are to blame for the collapse of the Afghan Republic in 2021, an epidemic of transnational crime was arguably one of the major contributing factors. Analyzing and drawing on secondary data from various sources, including national and international organizations and governmental institutions, this article explains the prevalence in the country of transnational crime (particularly the four critical crimes identified above) and how they have created a vicious circle through their mutual and reinforcing relationships. The article also assesses the devastating impacts of these transnational crimes on the security, economy, stability, rule of law, and legitimacy and authority of the Republic government, ultimately causing the government to crumble and cease to exist.</p>