Aluminum and its alloys are widely used in industries due to their favorable mechanical properties, low density, and natural passivation. However, they remain susceptible to corrosion in acidic environments, necessitating effective and environmentally friendly inhibition strategies. In this study, the corrosion inhibition behavior of two phenolic acid derivatives, vanillic acid (VA) and isovanillic acid (ISVA), on aluminum was investigated using a combined density functional theory (DFT) and molecular dynamics (MD) simulation approach. DFT calculations revealed that VA exhibits a higher HOMO energy, smaller energy gap, greater global softness, and larger fraction of electrons transferred compared to ISVA, indicating stronger electron-donating ability, higher chemical reactivity, and enhanced adsorption propensity. Fukui function analysis identified oxygen atoms in hydroxyl and carboxyl groups as primary reactive sites, with O (4), O (8), O (11), and O (12) in VA and O (11) in ISVA, highlighting the crucial role of oxygen-containing functional groups in adsorption. MD simulations confirmed strong adsorption of both inhibitors on the Al (111) surface, with adsorption energies of -0.692 eV (VA) and -0.706 eV (ISVA), and revealed favorable molecular orientation, surface coverage, and hydrogen bonding interactions stabilizing the protective layer. Integrating DFT and MD results, VA was identified as the more effective corrosion inhibitor due to its higher reactivity, multiple active adsorption sites, and stronger electron-donating capability. This study provides molecular-level insights into corrosion inhibition mechanisms and supports the rational design of environmentally friendly inhibitors for aluminum in acidic media.