This study examines the effects of chemical admixtures—a superplasticizer, an anti-sedimentation agent, and a defoaming agent—applied at various dosages and in different combinations, as a strategy to improve the workability of geopolymers while preserving their mechanical performance. Techniques such as TG-DTA, FTIR, XRD, MIP, nitrogen adsorption, SEM-EDX, and compressive strength testing were used to assess their impact. The findings emphasize the importance of careful selection and combination of admixtures and offer new insights for practical application. Except when all three admixtures were used together, the workability of the geopolymers improved, along with a significant reduction in open porosity and macropores. 28-day compressive strengths ranging from 41–74 MPa were lower than that of the reference geopolymer (77 MPa). Depending on the admixtures used, this reduction was linked to superplasticizer degradation, a lower degree of polymerization in the N-A-S-H gel, and weakened interfacial bonding caused by mullite particles randomly embedded within the gel.