Advanced HIV causes substantial mortality in sub-Saharan Africa despite widespread antiretroviral therapy coverage. This paper explores pathways of care amongst hospitalised patients with advanced HIV in rural Kenya and urban Democratic Republic of the Congo, with a view to understanding their care-seeking trajectories and poor health outcomes. Thirty in-depth interviews were conducted with hospitalised patients with advanced HIV who had previously initiated first-line antiretroviral therapy, covering their experiences of living with HIV and care-seeking. Interviews were audio-recorded, transcribed and translated before being coded inductively and analysed thematically. In both settings, participants' health journeys were defined by recurrent, severe symptoms and complex pathways of care before hospitalisation. Patients were often hospitalised after multiple failed attempts to obtain adequate care at health centres. Most participants managed their ill-health with limited support networks, lived in fragile economic situations and often experienced stress and other mental health concerns. Treatment-taking was sometimes undermined by strict messaging around adherence that was delivered in health facilities. These findings reveal a group of patients who had "slipped through the cracks" of health systems and social support structures, indicating both missed opportunities for timely management of advanced HIV and the need for interventions beyond hospital and clinical settings.