In this work, cellulose nanocrystals (CNC) derived from sawdust were successfully incorporated into a thin film composite membrane made from polyamide. The characteristics of unmodified and modified membranes were investigated using FT-IR, XRD, TGA, SEM, EDX, AFM and contact angle measurement. The membranes’ performances were evaluated using a dead-end test cell with sodium chloride (1500 ppm) and calcium chloride (2500 ppm) solutions. FT-IR and XRD analyses revealed that polymerization took place during the incorporation of the cellulose nanocrystals. From EDX analysis, it was found that incorporation of CNC into the membrane resulted in an increase in the oxygen content both at the atomic and mass levels. SEM and AFM images revealed dense and tight structures for both modified and unmodified membranes. The modified membrane was more hydrophilic and rougher than the unmodified membrane. The water flux was significantly increased (more than 23%) while maintaining high rejection rate values for sodium chloride (98.3 ± 0.8%) and calcium chloride (97.1 ± 0.5%). Furthermore, there was also an increase in the thermal stability of the membrane. The results, therefore, have shown a great prospect in the development of thin-film nanocomposite membranes using sawdust-derived cellulose nanocrystals incorporated in polyamide.