Abstract Pathological accumulation of senescent cells (SnCs) across tissues drives aging and age-related diseases. Senolytic agents targeting senescent cell anti-apoptotic pathways (SCAPs) hold promise for treating age-related diseases, yet their efficacy is limited by the heterogeneity of SnC survival mechanisms beyond canonical BCL-2 family pathways. Here, we identify intracellular complement C3 (intC3) as a previously unrecognized determinant of senolytic responsiveness.