Mitochondrial calcium (mCa2+) homeostasis also plays a key role in the buffering of cytosolic calcium (cCa2+) and calcium transported into the mitochondrial matrix regulates cellular metabolism, migration and cell fate decisions. Recent work has highlighted the importance of mCa2+ homeostasis in regulating cellular function. The discovery of the mCa2+ uptake complex has shed new light on the role of mCa2+ dynamics in cytoskeletal remodeling, mitochondrial shape and motility in cellular dynamics. Here we attempt to decipher the vast landscape of calcium regulatory effects of the mitochondria, the underlying mechanisms and the dynamics that control cellular function.