Comfort is vital in sportswear design. Previous research focused on the thermo-physiological comfort of modal blended fabric by examining its physical and thermal properties, neglecting comprehensive wear trials. This study compared the perceived comfort of two sportswear samples: polyester fabric and modal blended fabric. Ten participants (mean age = 22.4) wore the samples in random order during two trials. Each trial involved 25 min of treadmill running at a self-selected speed in a laboratory with a room temperature of 23.5 ± 1°C and 50% humidity. Heart rate, blood lactate level, skin temperature, perceived exertion, self-reported comfort, sportswear weight change, and fabric properties were recorded. Results showed that the blended fabric offered superior comfort despite the polyester fabric demonstrating better moisture transfer. This suggests that fabric composition and absorbency contribute to comfort and moisture transmission. Future studies should explore fabric structures and their impact on comfort in modal blended fabric using comprehensive human trials.