Accumulated evidence suggests that p53 plays an important role in the regulation of metabolism and intracellular redox homeostasis through transcription-dependent and -independent mechanisms. Mitochondria, the power plant of cells, provide cells with ATP for their functions by regulating energy metabolism. In addition, as the byproducts of metabolism, reactive oxygen species (ROS) generated in the mitochondria can serve as signaling molecules to regulate p53 function. The regulation of p53 by mitochondria, especially redox-mediated regulation, may be involved in controlling the cellular switch between survival and death. The interplay between p53 and manganese superoxide dismutase (MnSOD), an important mitochondrial antioxidant enzyme, is an example of how nuclear and mitochondrial p53 coordinate their response to different levels of stress and contribute to the fate of cells.