Tooth bleaching helps to improve the appearance of discolored teeth. But the use of acidic food can lead to increased erosion after bleaching. Remineralizing treatment with a remineralizing agent is capable of reestablishing the lost enamel surface hardness after bleaching. In this study, changes in microhardness were analyzed upon the application of a remineralizing agent after subjecting the enamel surfaces to bleaching and erosive challenge. Aim: The aim of this study is to evaluate the effect of a remineralizing agent on bleached enamel surfaces subjected to erosive challenge. Materials used: (1) 35% carbamide peroxide (Opalescence PF, Ultradent)—a bleaching agent; (2) Remin Pro—a remineralizing agent; (3) 1% citric acid solution—an erosive agent. Methodology: Samples were divided into three groups and subjected to bleaching and erosion treatment. Group I—treated with 35% carbamide peroxide then treated with 1% citric acid solution; group II —treated with 35% carbamide peroxide and a remineralizing agent followed by 1% citric acid solution; group III—without bleaching with 1% citric acid solution. The sample size calculated using the statistical package G*power (3.1.5) with a level of significance of 0.05. The sample size obtained is n = 15, 5 samples per group. G1, G2, and G3 were subjected to the Vickers microhardness analysis. Loss of surface hardness loss (% SHL) was analyzed. Result: The lowest % SHL is in group II—24.718 when compared with group I—35.048. Conclusion: Post-bleaching application of a remineralizing agent helps to decrease the effect of erosion occurring as a consequence of bleaching.