Considering the environmental challenges associated with Portland cement production, developing and enhancing the properties of geopolymer cement as a sustainable alternative has attained significant attention. This study investigates the three-objective optimization of mechanical and durability properties of geopolymer cement paste, including 28-day compressive strength, carbonation depth, and capillary water absorption, using the NSGA-III algorithm. Experimental data from 27 different geopolymer mixtures, produced using calcined clay, slag, and three activators (sodium hydroxide (NO), sodium carbonate (NC), and sodium silicate (WG)), served as inputs. The three decision variables in this study are the type of activator, the ratio of activator solution to precursor material, and the percentage replacement of calcined clay with slag. Through multi-objective optimization, four optimal mixtures were extracted from the experimental data. In all combinations, the ratio of solid activator solution to precursor material was determined to be 0.1. The first mixture, containing sodium hydroxide with 1.5% calcined clay replacement, exhibited a compressive strength of 25.05 MPa, carbonation depth of 10.58 mm, and capillary water absorption of 938×10⁻⁷ (mm/s0.5). The second mixture, with similar characteristics but 1% calcined clay replacement, demonstrated the lowest carbonation depth of 10.07 mm. The third mixture, containing sodium silicate, recorded the highest compressive strength of 63.35 MPa and the lowest capillary water absorption of 195×10⁻⁷ (mm/s0.5). This composition showed superior performance due to its denser structure and optimized geopolymerization reactions. The fourth mixture, containing sodium hydroxide with 2% calcined clay replacement, exhibited a compressive strength of 25.50 MPa and capillary water absorption of 948×10⁻⁷ (mm/s0.5). Compared to ordinary Portland cement, the optimized geopolymer mixtures provided desirable performance in certain aspects, particularly in compressive strength and carbonation resistance. However, their capillary water absorption remained higher.