The effect of zinc oxide on the corrosion inhibition of mild steel embedded in concrete in 3.5% sodium chloride solution was investigated using potential measurement, pH and gravimetric methods. The experiments were performed using zinc oxide as the inhibitor in 3.5% NaCl solution. From 200g of ZnO powder, and using distilled water, 25, 50, 75, and 100% zinc oxide inhibitor concentrations were prepared. A digital voltmeter was used to record potential measurements. A copper-copper sulphate electrode was used as the reference electrode. After the experiments, compressive strength of each block sample was determined. Weight loss values were obtained from the weight loss method and the inhibitor efficiency was calculated from the corrosion rate of each of the tested samples. The results were further analysed using the two-factor ANOVA test. Results showed varied concentrations of ZnO inhibitor and the test exposure time significantly affected the corrosion potential of the embedded steel rebar. The inhibitor gave appreciable corrosion inhibition performance of the embedded steel rebar at 100 and 75% concentrations with the weight loss of 600 and 800mg and corrosion rates of 0.000270 and 0.000357mm/yr respectively. An inhibitor efficiency of 41.02% was achieved at 100% ZnO concentration. ANOVA analysis confirmed the results at 95% confidence.