The dyeing process commonly deteriorates the luster of pre-mercerized cotton fabric, so post-mercerization processes are regularly applied to compensate for this. Herein, the influence of combining pre-mercerization with CS (caustic solution) or LA (liquid ammonia) and post-mercerization with CS or LA on the morphological structure, dyeing performance, tensile strength, and stiffness of woven cotton fabric was investigated. The crystallinity index values greatly decreased from 73.12 to 51.25, 58.73, 38.42, and 40.90% after the combined mercerization processes of LA–LA, CS–CS, LA–CS, and CS–LA, respectively. Additionally, the CS–LA- and LA–CS-treated samples exhibited a mixture of cellulose II and cellulose III allomorphs. The combined mercerization processing of cotton fabric resulted in slightly worse thermal stability. The LA and CS pre-mercerization processes increased the dye exhaustion, although the former decreased the dye fixation rate while the latter increased it by 4% for both dyes. The color strength of the dyed cotton fabric increased after both post-mercerization processes. Moreover, the fabric stiffness and mechanical properties showed an increasing trend due to the combined mercerization efforts.