The present study aims to assess the potential of three pyrimidine derivatives—namely, ethyl 4-[4-(dimethylamino)phenyl]-2-imino-6-methyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate (EDTP), 1-{4-[4-(dimethylamino)phenyl]-2-imino-6-methyl-1,2,3,4-tetrahydropyrimidin-5-yl}ethan-1-one (DITP), and 4-[4-(dimethylamino)phenyl]-2-imino-6-methyl-N-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DPTP)—in protecting mild steel against acidic corrosion. The anti-corrosive effectiveness of these synthesized pyrimidine derivatives is evaluated using various electrochemical techniques. Based on the electrochemical findings, it is observed that all synthesized pyrimidine derivatives function as mixed-type inhibitors. Notably, DPTP demonstrates superior efficacy at 750 ppm (91.7 %) in comparison to EDTP (88.9 %) and DITP (88.4 %). Analysis utilizing the Langmuir isotherm model reveals the most precise correspondence with the studied derivatives, suggesting a mixed mode of adsorption involving both chemisorption and physisorption. Furthermore, a surface analysis investigation is conducted to assess the morphology of metallic surfaces exposed to varying inhibitor concentrations within an acidic environment. To corroborate the experimental findings, theoretical approaches including Monte Carlo simulation (MC simulation) and density functional theory (DFT) have been employed.