In 2021, an estimated 3.95 million foreign nationals resided in South Africa, with no data available on numbers of displaced persons or undocumented migrants residing without legal or valid immigration status. Surveillance data on immigration detention are scant. We present a socio-legal account of the historical evolution of South African immigration detention regulation in post-apartheid timeframes, with a view to providing a legal realist assessment of the socio- and politico-legal dimensions pertinent to human rights assurances of immigration detainees in South Africa. The realist focus is on scrutinizing South Africa’s progress in upholding the rights of immigration detainees and illustrating the contemporary complexities in ensuring due process in the (co)application of the Immigration Act (and Refugees Act) explicitly regarding immigration detention processes and practices. We present the applicable international and regional African human rights treaties, domestic regulations, and relevant jurisprudence to the rights of immigration detainees in South Africa. The generated realist narrative is cognizant of the contextual forces of migration into South Africa, securitization agendas, and violations of basic human rights and due process, and illustrates various gaps in the application of domestic laws, policies, and standards of care regarding immigration detention when evaluated against the rule of law.