This article explores the intricate relationship between transnational solidarity and citizenship in socialist Tanzania, renowned for its extensive and enduring support of liberation movements from the 1960s to the 1980s. Termed “frontline citizenship”, this unique political subjectivity, evolving in the 1960s, was shaped not only by Tanzania's geopolitical location, nationalist struggles against colonialism, and government efforts to instil attitudes of anti-colonial solidarity in the population, but also by initiatives of hosted liberation movements, Tanzanians’ embrace of global anti-imperialist currents from Cuba to China and Vietnam, and critiques of politicians in exile. The article highlights the gendered and generational aspects of the solidarity regime, scrutinizes contested material solidarities, and discusses the partial decline of the frontline citizenship discourse. It does so by investigating the role of media, the impact of the paramilitary National Service, and the dynamics of material support practices. Drawing on multi-archival research, interviews, memoirs, and secondary literature, with a focus on South Africa's African National Congress (ANC), the analysis challenges conventional views of state-sponsored solidarity, emphasizing the dynamic interplay between state initiatives and grassroots participation as well as “external” and “internal” actors. Conceiving socialist Tanzania's solidarity regime in this way contributes to a broader understanding of the intersection between anti-imperialist world-making, nationalist state-building, and everyday performances of citizenship.