In this work, smart nanocontainers were prepared by polyelectrolyte deposition on SiO2 nanoparticles to encapsulate corrosion inhibitors, i.e., benzotriazole (BTA). Various materials analysis techniques, including Fourier transform infrared, thermal gravity analysis and atomic force microscopy, were used to characterize the nanocontainers and confirm the loading of BTA. The pH selectivity for self-releasing of BTA out of the nanocontainers was determined by measurements of electrochemical impedance spectroscopy. At either low or high pH value (e.g., pH 2 or 11), the inhibitors release to prevent a carbon steel from corrosion in chloride solutions. In near-neutral pH from 5 to 9, the nanocontainers remain closed. The BTA molecules follow the super-relaxational transport mechanism to release from the nanocontainers by swelling-controlled releasing processes. The inhibition efficiency is subject to the releasing kinetics of the inhibitors. The Korsmeyer-Peppas model provides estimation of the inhibitor-releasing rate.