• Novel amino acid derivatives P-Meth and P-Cys were synthesized via a one-step acylation, achieving corrosion inhibition efficiencies of 95.6% and 93.1% for Q235 steel in 1 M HCl, respectively.
• The derivatives significantly reduce corrosion rates (from 4.542 to 0.202 and 0.312 mg·h−1·cm−2) and enhance charge transfer resistance by 12-fold and 9-fold, respectively.
• Adsorption on the steel surface is predominantly chemical, with minimal physical contribution, as confirmed by experimental and theoretical analyses.
• Molecular dynamics simulations reveal higher binding energy for P-Meth, correlating with its superior inhibition performance, offering a green and cost-effective corrosion protection strategy.