The growing emphasis on sustainable construction has led to the investigation of one-part alkali-activated (OP-AA) materials, which are promising alternatives to conventional binders. This study focuses on optimizing the properties of OP-AA paste blends, including slump flow, setting time, and compressive strength, using Taguchi and the technique of ordering preferences by similarity to ideal solution (TOPSIS) methodologies. A three-factor, three-level experimental design with an L9 orthogonal array was employed to evaluate the impact of ground-granulated blast furnace slag to fly ash ratio (S/F), water-to-binder ratio (W/B), and sodium oxide (N) percentage. Multi-objective optimization through TOPSIS identified the optimal parameter levels at S/F = 1, W/B = 0.35, and N = 6%, achieving a slump flow of 200 mm, an initial setting time of 58 min, a final setting time of 190 min, and a 28 day compressive strength of 41.51 MPa. The results demonstrate the effectiveness of Taguchi and TOPSIS in optimizing binder properties for improved workability, setting behaviour, and strength development. This study provides a systematic approach for enhancing OP-AA binder performance, laying the groundwork for further investigations into sustainable binder systems.