The simple operation of one-part geopolymer has shown promising practicability for future in-situ construction similar to ordinary Portland cement. Intending to meet the demand of various industrial applications such as 3D printing, this study aims to tailor the early-age properties of one-part fly ash/ground granulated blast-furnace slag (FA/GGBS) geopolymer through the utilization of hybrid activators, such as anhydrous sodium metasilicate (Na₂SiO₃), sodium carbonate (Na₂CO₃), and sodium aluminate (NaAlO₂). The reaction kinetics and chemistries of such alkali activators are expounded to understand the working principles and their contribution to the performance improvement of one-part geopolymer. The experimental results indicated that Na₂SiO₃-activated one-part geopolymer released high reaction heat and achieved a faster setting. Such shortcomings could be improved by partial replacement of Na₂SiO₃ with Na₂CO₃ in a solid form. Besides, the incorporation of slight NaAlO₂ decreased the self-flow of geopolymer paste, whereas the slump-flow properties remained unchanged.