This study investigates the influence of nanocellulose fibre (CF) derived from wood pulp on the hydration, mechanical, shrinkage, and pore properties of ordinary Portland cement (OPC) mortar. The CF was incorporated into mortar mixes at varying dosages (0.15–1.5% by weight of mortar) to evaluate its effect on physical, mechanical, and microstructure properties. …The results suggest that an optimal CF dosage of 0.45% provides a balance between workability, mechanical properties, and durability, making it an effective additive for enhancing the performance of OPC mortars in sustainable construction applications. The study promotes the use of recycled cellulose fibres in mortars, which helps reduce the reliance on non-renewable resources. By carefully managing CF content, it is possible to achieve an acceptable balance between workability, mechanical strength, and durability.