The essential oil of Psidium guajava L. has been studied for pharmacological and industrial purposes, without considering the plant's genotype regarding the heterogeneity of its composition. The present study aimed to characterize the chemotype diversity of the essential oil extracted from the leaves of 22 genotypes of P. guajava grown in two different environments in the state of Espírito Santo, Brazil, and to identify the different chemical markers present in these plants. Essential oil from the leaves of the P. guajava genotypes was extracted by hydrodistillation, and its chemical composition was analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Thirty-three compounds were identified, comprising 87.5-99.0% of the total composition, with a prevalence of sesquiterpenes in all samples. The major compounds identified consisted of (E)-trans-Caryophyllene, α-Humulene, trans-Nerolidol, β-Bisabolene, β-Bisabolol, and Hinesol, the first of which was identified as a possible chemical marker for the species. Multivariate factor analysis of the chemical composition of P. guajava oil identified three chemotypes: Commercial - PAL, SEC, PS, PET, C7, C11, and C17MI, characterized by high levels of β-Selinene, α-Selinene, Hinesol, and 14-hydroxy-epi-(E)-caryophyllene, with β-Selinene and α-Selinene as the chemical markers; C10 and C13, exhibiting high levels of Elemol, trans-Nerolidol, trans-β-Eudesmol, and (2Z, 6Z)-Farnesol, which were indicated as chemical markers, and Cortibel - C1, C2, C3, C4, C5, C6, C8, C9, C12, C14, C15, C16, C17LI, which retained high levels of α-Cedrene, cis-α-Bergamotene, α-Humulene, Humulene epoxide, epi-α-Cadinol, β-Bisabolol, and α-Bisabolol, with β-Bisabolol and α-Bisabolol as the chemical markers. The use of guava genotypes with different chemotypes, that are agronomically favorable to fruit production and essential oil exploitation adds value to the crop and renders it more sustainable. Given guava crops produce large amounts of leaf biomass, resulting from successive prunings, the extraction of their essential oil, which retains commercially valuable compounds, can be feasible.