<p>Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants associated with significant ecological and human-health risks. In this work, the adsorption and sensing potential of B₃O₃ nanoflakes toward representative PAHs, namely benzene, naphthalene, anthracene, and pyrene, was investigated using a multilevel computational approach combining density functional theory (DFT), Monte Carlo simulations, and quantum chemical analyses. The calculated adsorption energies, ranging from approximately −&#xa0;14 to −&#xa0;30&#xa0;kcal&#xa0;mol⁻¹, indicate favorable physisorption, with stronger adsorption observed for larger and more π-conjugated PAHs due to enhanced dispersion-assisted π-π interactions and increased adsorbate–surface contact area. Adsorption induces notable electronic perturbations in the B₃O₃ nanoflake, including reductions in the HOMO–LUMO gap, Fermi-level shifts, and dipole-moment changes, suggesting a possible electronic response toward PAH adsorption. QTAIM, NBO, Mulliken charge, and RDG/NCI analyses confirm that the interactions are dominated by noncovalent van der Waals forces, weak π-surface interactions, and minor interfacial polarization, without evidence of covalent bond formation. Recovery-time estimates suggest fast desorption for benzene and moderate desorption for naphthalene, whereas stronger adsorption of anthracene and pyrene may require external stimulation for efficient sensor regeneration. Overall, the results identify B₃O₃ nanoflakes as promising theoretical candidates for PAH adsorption and possible sensing applications, although further DOS/PDOS, periodic electronic-structure, and transport-level studies are required to validate practical sensor performance.</p>