The CO2 gas released from the chimneys to the atmosphere during cement production causes global warming and threatens the environment. Therefore, scientists work on fly ash-based polymers to minimize carbon emissions and reduce the need for Portland cement in the construction industry. Today, the use of geopolymer mortars as a partial alternative material to replace cementitious mortars is being investigated. In this study, the effect of zeolite admixture on the mechanical properties of fly ash based geopolymer mortars which are poured into 40x40x160 mm prism molds activated with alkali and heat (90oC) was investigated. Firstly, F type fly ash from "Isken Sugözü Power Plant", NaOH (98% purity) and Na2SiO3 (50% purity) and Rilem-Cembureau Standard Sand were mixed in various proportions and zeolite-free geopolymer mixture ratios with the highest strength were determined. Then, the zeolite additive was applied in various proportions of the fly ash in the geopolymer mortar with the highest strength. In order to increase flexural and compressive strengths with different amounts of zeolite additives, experiments were made by changing the amount of alkali activator and alumina silicate in the mixture. At the end of the research, one-day bending and compressive strengths of all samples were determined, and although adding zeolite as an additive into geopolymer mortar does not give strength-increasing strength parameters, it was found that zeolites can be used as green building mortars with lower environmental harmful effects than cement due to their heavy metal ions removal properties.