In this article, the effect of metakaolin (MK) and slag as supplementary cementitious materials in the concrete was investigated. For this purpose, the measurements of compressive strength, rapid chloride penetration test (RCPT), open circuit potential (OCP), macrocell corrosion current (MCC), and total integrated corrosion current (TICC) were carried out for the concrete prepared with two different binders, two types of steel, three water/binder ratios, and three sodium chloride (NaCl) exposures. From the outcome of this investigation, it can be concluded that the concrete prepared with MK has better corrosion resistance as compared to the concrete prepared with slag.