This community process evaluation highlights key enabling factors that facilitated the implementation of a community peer education program for youth HIV prevention in four poor and vulnerable areas of Aden, Yemen. It also explains the implementation process and provides a deeper understanding of the impact evaluation outcomes, which revealed improved HIV knowledge and risk perception and decreased stigma and risky behavior. This process evaluation was based on qualitative methodologies, where five focus group discussions and 15 in-depth interviews were conducted among 52 participants: community peer educators, community focal points, targeted young people, and local councils. The results revealed that contributing factors to implementing the peer education program had been community participation, mobilization of targeted communities, and capacity building of all those included in the intervention. Existing community-based organizations like the Social Service Centre played a key role in building trust with the targeted communities and linking HIV peer education intervention to other existing community services. This process evaluation could provide lessons learned for replicating similar youth peer education programs in conservative communities.