<p>The increasing surplus of cotton fibers presents an opportunity for sustainable reuse in cementitious materials. This work investigates the effects of curing regime on the mechanical and physical properties of Controlled Low-Strength Material (CLSM) reinforced with various types of cotton fibers. CLSM mixtures with different water–cementitious (w/cm) ratios were prepared and subjected to distinct curing conditions to evaluate their effects on key performance parameters, including compressive strength, indirect tensile strength, and drying shrinkage. Results show that cotton filler enhances tensile performance and reduces shrinkage, while the curing regime plays a significant role in the rate and extent of strength development. Optimal performance was achieved under controlled moisture-curing conditions at moderate w/cm ratios, yielding improved mechanical stability and reduced cracking potential. The integration of cotton fibers also maintained acceptable flowability, making the modified CLSM suitable for backfill and structural support applications. Utilizing cotton waste in CLSM provides a sustainable and cost-effective approach to material improvement, aligning with circular economy principles. The combined effects of fiber reinforcement and optimized curing regimes demonstrate the potential of cotton-reinforced CLSM as an environmentally responsible material for construction and infrastructure applications.</p>