There is growing international concern over the nexus between transnational organized crime, and terrorism – a significant, complex, and dynamic threat to global security. Considerable evidence from different regions in the world, such as South America and Sub-Saharan Africa, suggests that there has been greater collaboration between terrorist groups and transnational criminal networks in the trafficking of narcotics and arming of terrorist groups. Complex as implementing legislation and law enforcement operations are limited in capacity and dynamic as this nexus keeps changing. The burden of proof in convicting such crimes has remained challenging, with law enforcement often preferring to use penal code than anti-terrorism instruments. Thus the scale of this nexus has not been verified systematically by frontline state agencies and non-state experts. This paper assesses challenges, achievements, and solutions to address the nexus between transnational organized crime and terrorism in East Africa. In so doing, the report explores ways in which transnational organized crime and terrorism are linked. Addressing this linkage is a priority for many countries in East Africa, one of the regions most affected by terrorism and transnational organized crime in Africa.