The global development financing landscape is undergoing a structural transformation characterized by increasing volatility in Official Development Assistance (ODA), driven by geopolitical priorities, in-donor refugee expenditures, and heightened humanitarian crisis responses. Although aggregate ODA levels have reached historic highs, these reallocations have reduced predictable, country-programmable development financing for low- and middle-income countries (LMICs), exposing civil society organizations to growing financial uncertainty. This study examines domestic resource mobilization (DRM) as a strategic mechanism for strengthening nongovernmental organization (NGO) resilience, autonomy, and sustainability within this evolving aid environment. Grounded in political economy of aid theory, endogenous development theory, and social capital frameworks, the study employs a qualitative comparative case study approach examining three Kenyan civil society organizations: Shining Hope for Communities (SHOFCO), Kenya Community Development Foundation (KCDF), and Malindi Education and Development Foundation (MEDA-F). Through document analysis, policy review, and thematic synthesis, the research evaluates how diversified DRM strategies, including community philanthropy, endowment development, digital fundraising, corporate partnerships, volunteer mobilization, and social enterprise financing, contribute to institutional sustainability and program continuity. Findings indicate that organizations institutionalizing diversified, locally anchored financing ecosystems demonstrate greater resilience to donor volatility, enhanced community accountability, and improved development effectiveness. The study concludes that hybrid financing models integrating DRM with catalytic international assistance provide a viable pathway toward resilient, locally driven, and sustainable development institutions.