Traumatic brain injury (TBI) represents a major cause of mortality and disability worldwide, particularly affecting young adults and elderly populations. This study investigates the neuroprotective potential of orlistat (ORL), a gastrointestinal lipase inhibitor, in a murine TBI model. Behavioral, histological, and molecular analyses demonstrated that ORL significantly attenuated TBI-induced neurological damage. Microglial depletion experiments revealed that ORL’s neuroprotective effects were largely mediated through microglial modulation. In vitro and in vivo studies showed that ORL suppressed microglial activation, phagocytosis, and migration. Single-cell RNA sequencing identified upregulation of lipoprotein lipase (LPL) in a TBI-induced microglial subpopulation. Molecular docking predicted ORL-LPL binding, suggesting direct enzymatic inhibition. Transcriptomic and metabolomic analyses further revealed ORL’s modulation of microglial metabolic pathways and inflammatory responses. Our findings position ORL as a promising repurposed therapeutic for TBI through its novel mechanism of targeting microglial LPL-mediated neuroinflammation.