Flexible pressure sensors are increasingly popular because of their extensive applications in smart textile and flexible robotics. Inspired by the composite hierarchical structure of conventional pillows, a pillow-shaped 3D hierarchical piezoresistive pressure sensor is presented in this work. Silver components-coated knitted fabrics and assembly of polypropylene fibers were employed to fabricate the textile-based pressure sensors using a facile thermal bonding route. The intrinsic flexible knitted structure and good resilience of polypropylene assembly synergized to render outstanding sensing performance, high sensitivity (3.504 kPa(-1)), and excellent durability (resistance reduction of 2%) even after 4500 cycles. Our pressure sensors were tested to monitor human's physiological activities, such as respiratory rate and extended sleeping position. Therefore, our proposed flexible sensors could provide a novel, convenient, and elegant solution to monitor the physiological activities of not only patients but also of healthy subjects such as children and the elderly.