Cells differentiate into specific and functional lineages to build up tissues. It has been shown in several tissues that mitochondrial morphology, levels of "mitochondria-shaping" proteins, and mitochondrial functions change upon differentiation. In this review, we highlight the significance of mitochondrial dynamics and functions in tissue development, cell differentiation, and reprogramming processes. Signalling cascades are critical for tissue stem cell maintenance and cell fate determination, and growing evidence demonstrates mitochondria could act as a centre of intra and extracellular signals to coordinate signalling pathways, such as Notch, Wnt, and YAP/TAZ signalling. Just an organelle, however, emerges as a master regulator of cell differentiation, and can be a target to manipulate cell fates. (C) 2017 Elsevier Inc. All rights reserved.