Recently, clothing comfort and ease of use have become an indispensable expectation especially in sports and functional clothing which have led researchers to focus on development of smart textiles including new functionalities such as active thermoregulation. Therefore, a novel nanocomposite finishing treatment consisting of temperature responsive shape memory polyurethane (SMPU) and cellulose nanowhiskers (CNWs) was developed and applied to polyester fabric to produce smart fabric having dual responsive performance to moisture besides temperature. Water vapour, air permeability and sweat absorption properties were investigated under different temperature and relative humidity conditions to test thermoregulation performance of the treated fabrics. Physical, mechanical properties (weight, thickness and bursting strength) and durability of treated fabrics were also tested. Morphology, chemical compositions and thermal characterization of treated fabrics were investigated by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimeter (DSC) and Thermogravimetric (TG) analyses, respectively. It was found out that polyester fabric exhibited dynamic breathability and sweat absorption with temperature and relative humidity of body or environmental conditions thanks to the obtained dual responsive shape memory function. Also, mechanical and end use performances such as bursting strength and washing fastness of polyester were enhanced with this treatment. Summing up, SMPU-CNW nanocomposite treatment can be a good alternative for smart sports clothing having thermoregulation function for enhanced comfort besides desired mechanical and end use performances.