Metabolism lies at the heart of cell biology. The metabolism of cancer cells is significantly different from that of their normal counterparts during tumorigenesis and progression. Elevated glucose metabolism is one of the hallmarks of cancer cells, even under aerobic conditions. The Warburg effect not only allows cancer cells to meet their high energy demands and supply biological materials for anabolic processes including nucleotide and lipid synthesis, but it also minimizes reactive oxygen species production in mitochondria, thereby providing a growth advantage for tumors. Indeed, the mitochondria also play a more essential role in tumor development. As information about the numorous microRNAs has emerged, the importance of metabolic phenotypes mediated by microRNAs in cancer is being increasingly emphasized. However, the consequences of dysregulation of Warburg effect and mitochondrial metabolism modulated by microRNAs in tumor initiation and progression are still largely unclear.