Background: Enrollment in sub-national social health insurance schemes (SSHIS) can be challenging in developing countries like Nigeria, particularly among people in the informal sector. This could be due to a lack of knowledge on its mode of operation and benefits, distrust in government, inimical religious and traditional beliefs, as well as constraining economic factors. A complementary and innovative financing strategy such as the philanthropist adoption model (ADM) could be beneficial in improving SSHIS coverage and financial resources among persons in the informal sector. The study provides new evidence on how ADM influenced health insurance coverage and resources within SSHIS among informal settings in Nigeria. It also highlights contextual factors influencing the implementation of ADM.