Parvalbumin-positive (PV+) interneurons within the hippocampal system are crucial for maintaining spatial memory functions that are otherwise impaired in neurodegenerative diseases. To maintain such an extensive control, PV+ interneurons require a high energy demand, which requires highly functional mitochondria. Previous studies have shown dysregulations of mitochondria within the hippocampus (HPC) are apparent early on in cases of Alzheimer’s Disease (AD), even preceding the major pathological hallmarks: tau aggregation, amyloid-beta plaques, and impairments in memory. Optogenetic tools have been instrumental in discovering and understanding the function of neurons within various different brain networks. Recently developed methods have expanded their use to allow for light-control of intracellular organelles, such as mitochondria. To understand how the mitochondria of PV+ interneurons contribute to learning and memory functions regulated by the hippocampal circuit, we utilized a previously developed optogenetic construct, mitoChR2, which targets the inner mitochondrial membrane. In the presence of light, the channel opens and causes a disruption of the proton motive force that drives ATP production, thus decreasing the amount of ATP produced, in essence “de-energizing” mitochondria. Through the use of this technique in conjunction with performing electrophysiological recordings in freely moving PV-Cre mice, we discovered “de-energized” mitochondria impaired the firing activity of interneurons and consequentially altered spatial properties of place cells within the HPC during exploration of a familiar environment. Our findings emphasize the importance of mitochondria in learning and memory mechanisms, and suggest mitochondria be considered for potential therapeutic targets for the treatment of AD.