Updated project metadata. Acclimation to different light regimes is at the base of survival for photosynthetic organisms regardless their evolutive origin. This study investigated the consequences of acclimation to different irradiances in Chlorella vulgaris, focusing on both photosynthetic and mitochondrial activities. Proteomic analysis of cells acclimated to high light or low light allowed to identify the main targets of acclimation in terms of differentially expressed proteins. The results obtained demonstrate photosynthetic adaptation to high vs. low light. Increased mitochondrial respiration measured in high light acclimated cells mainly relied on alternative oxidative pathway dissipating the reducing power produced in excess due to enhanced carbon flow. Finally, proteins involved in cell metabolism, intracellular transport, gene expression and signaling, were identified as strongly differently expressed in high vs. low light suggesting their key role in acclimation to different light regimes.