Background: Brain is the main organ that manages all other organs and has significant oxygen requirements, which makes it vulnerable to reactive oxygen species, thus causing different neurological disorders. The aim of this work is the evaluation of Lavandula officinalis essential oil neuroprotective effect against hydrogen peroxide (HP)-induced toxicity in mice. Materials and Methods: Essential oil was extracted by hydrodistillation using a Clevenger-type apparatus. Essential oil analysis is performed using gas chromatography-mass spectrometry (GC-MS). Biological activity evaluation carried out the ferric reducing antioxidant power test, deoxyribonucleic acid (DNA) fragmentation assay, the histopathological study of the brain, and determination of antioxidant enzyme activities. Results: Chemical characterization of essential oil using GC-MS identified 47 compounds, accounting for almost 80% of the total oil and indicates the occurrence of monoterpenes and sesquiterpenes. The identified major compounds are pentanone (16.55%), propanal (15.89%), methyl ethyl ketone (13.51%), naphthalene (10.81%), terpinen-4-ol (6.55%), cyclopentanecarboxylic acid (4.77%), and isoborneol (2.27%). This study allowed us to investigate the effects of HP on brain function in Mus musculus adult mice by assessing DNA degradation, cell morphology, oxidative balance and brain weight variation. Furthermore, we have highlighted the beneficial effects of L. officinalis essential oil, which could significantly counteract all these alterations by its active compounds, which are endowed with potent biological activities. Conclusion: We can conclude that HP-induced damage in histomorphological changes in mice brain, significant atrophy, as well as an important alteration of the genetic expression.