Abstract The port city of Havana, central to the Spanish colonial fleet system since the late sixteenth century, remained an important nexus for nineteenth-century Atlantic trade networks of sugar, coffee, tobacco, and the slave trade. Positioning Irish immigrants in this global hub allows us to examine their presence in Cuba and their participation in global circuits of commodities, trade, and labor. Drawing on local colonial sources, we evaluate the opportunities and experiences of Irish immigrants as social actors in the multi-ethnic urban spaces of Havana and other strategically located port cities of Santiago and Cienfuegos. The Irish who converged on Cuba rarely came directly from Ireland. Hence, we explore three migration trajectories mediated through the British West Indies, the Spanish metropole, and globally connected cities of North America. The most prominent were high-ranking military men who arrived in Cuba in the eighteenth century through Iberian-Irish connections; a smaller number of propertied Irish who migrated from the West Indies; and lastly, distinct flows of largely anonymous nineteenth-century immigrants who came through emerging Atlantic networks of colonial labour via the United States. This study explores the entangled histories of Irish, African, and European diasporas in the social and political worlds of three Spanish Caribbean port cities. Through an analysis of how Irish immigrants negotiated processes of class, religion, race, and gender in colonial Cuba, we highlight their participation in key economic and social dynamics of white colonization strategies, plantation slavery, and the Atlantic slave trade.