Mitochondria provide energy and maintain homeostasis, and their dysfunction relates to aging. Disrupted structure and function of mitochondria are linked to age-related diseases, but the roles of many mitochondrial proteins in mitochondrial dynamics and aging remain unclear. We studied the role of the mitochondrial fission protein MTP-18 in mitochondrial dynamics and aging in C.elegans. Our data show that loss of mtp-18 increases longevity and stress resistance, alongside changes in key physiological processes. We tested whether mtp-18-mediated longevity is linked to the PI3K-dependent insulin/IGF-1 signaling (IIS) pathway. mtp-18-mediated longevity requires the Forkhead transcription factor DAF-16, a primary effector of the IIS pathway, but is not mediated by the canonical IIS cascade. We also observed unique interactions between mtp-18 and genes encoding components of the mobile electron carrier system in mitochondria, such as coenzyme Q and cytochrome c. Our study reveals that mtp-18 is an evolutionarily conserved, key aging regulator that maintains mitochondrial morphology. What sets this study apart from previous research is the identification of a novel mechanism by which MTP-18 affects these processes independently of the canonical IIS pathway, particularly through unique interactions with genes encoding components of the electron transport chain.