Mitochondrial quality control includes mitochondrial biogenesis, fusion, fission (to maintain mitochondrial function), and mitochondrial autophagy (for removing damaged mitochondria). This is a highly delicate and complex process involving many molecules. Mitochondrial quality control is crucial for maintaining mitochondrial homeostasis and function, preserving energy supply, eliminating damaged mitochondria to prevent cytotoxicity, promoting mitochondrial regeneration and repair, protecting cells from oxidative stress and senescence, and facilitating cellular communication and material exchange. In this review, we introduce the structure and function of mitochondria, the mechanisms of quality control, and the relationship between mitochondrial quality control and cellular processes such as pyroptosis, apoptosis, and ferroptosis. We also summarize the proteins, enzymes, and their molecular mechanisms involved in these processes and propose a “spatiotemporal-threshold” model for the mitochondrial quality control–cell death axis.