Concrete is considered the backbone material in the construction field. Cement manufacturing emits huge amounts of CO2 into the atmosphere. Also, the concrete deterioration in aggressive environments is one of its disadvantages. Thus, finding new eco-friendly construction materials for green and sustainable construction is very essential. The geopolymer (GP) based materials can be employed as eco-friendly sustainable construction materials. Many research works studied the fresh and the mechanical properties of the GP based systems but its durability has not been covered well. This paper studies the corrosion resistance of the GP mortars. The following parameters have been studied: the molarity of NaOH (6, 10, 16 and 20); the Na2SiO3 to NaOH ratio (1, 2.5 and 4.5); the alkaline solution to fly ash ratio (0.4, 0.5 and 0.6); the curing temperature (25◦C, 60◦C and 90◦C); the rest period (0, 24 and 48 hours) and finally the extra water as a percentage of fly ash (10%, 12.5% and 15%). The results showed that there are optimum conditions for the investigated parameters to achieve the highest values for the desired mechanical properties of the considered GP mortar mixes. The corrosion resistance evaluated by half-cell, current intensity readings and periods to the first crack are affected by the investigated parameters. Increasing the molarity of the used solution, reducing the solution to fly ash ratio and reducing the percentage of extra water enhanced the corrosion resistance.