Chondrosarcomas are common bone sarcomas frequently resistant to radiation and chemotherapy, with high recurrence rates, development of metastatic disease, and death. Fibrosarcomas are soft tissue sarcomas associated with poor outcomes. Translocase of outer mitochondrial membrane receptor 20 (TOMM20) is a mitochondrial receptor protein associated with cancer aggressiveness in many cancer subtypes, but the mechanisms remain poorly understood. Here, we studied the effects of TOMM20 overexpression and downregulation on the redox state, mitochondrial oxidative phosphorylation (OXPHOS), and tumor growth using fibrosarcoma and chondrosarcoma models. TOMM20 overexpression increased OXPHOS, NADH, and NADPH with reduced cellular reactive oxygen species (ROS). TOMM20 induced resistance to apoptosis, including with BCL-2 and OXPHOS complex IV inhibitors, but with increased sensitivity to an OXPHOS complex I inhibitor. Also, TOMM20 induced cell growth and migration in vitro and promoted tumor growth in vivo. Conversely, knocking down TOMM20 using CRISPR-Cas9 reduced cancer aggressiveness in vivo in both chondrosarcoma and fibrosarcoma mouse models. In conclusion, TOMM20 is a driver of cancer aggressiveness by OXPHOS, apoptosis resistance, and the maintenance of a reduced state.