Within the conceptual discussions of ‘Muslim diaspora’, the intersection between cultural blackness and Islam has received little attention. Yet its investigation is necessary to understand the increasing conversion to Islam among people who associate themselves with cultural blackness. In this context, Islam seems to offer new means for resistance and liberation, and contributes to transnational countercultures directed against racism and socio-economic marginalisation in post-colonial societies. Using Gilroy’s ideas of ‘the Black Atlantic’ and ‘diaspora’, we aim to develop an analytical framework to understand processes of black Muslim identity formation. The empirical foundation is provided by two case studies in Brazil and South Africa that focus on social groups who reproduce specific ideas of transnational ‘Muslim blackness’. A comparison of these allows us to offer an analytical framework for research on a ‘blackandMuslim diaspora’ as a transnational counterculture.