Long before the current refugee crisis, third sector organizations (TSOs) have played a pivotal role in dealing with the multifaceted challenge of migration. Researchers have analyzed this role in many ways. What is missing, however, is a comprehensive overview of how the third sector contributes to dealing with migration. To close this gap, we conduct a systematic literature review (SLR) that maps the scholarly debate on TSOs and migration. Our SLR identifies four domains of TSO migration engagement: first, the direct provision of basic services and social welfare; second, migrant-oriented capacity development; third, system-oriented advocacy; and fourth, complementary research activities. We propose a conceptual framework that highlights the contribution of TSOs with regard to individual-oriented and system-oriented services that are necessary for a successful integration of migrants. A key implication of our derived framework is to understand migration as a holistic challenge that requires contributions by different actors on different levels, thus highlighting the need for coordination and communication between the TSOs, the state and other stakeholders.