The primary organelle where ATP is produced is the mitochondrion. Often referred to as the "powerhouse of the cell," mitochondria carry out cellular respiration, converting nutrients into ATP through the process of oxidative phosphorylation. They are equipped with an inner membrane that hosts the electron transport chain and ATP synthase enzymes, which are essential for ATP production. The efficient functioning of mitochondria is vital for meeting the energy demands of the cell, enabling various biological processes.