Textile strain sensors capable of monitoring human physiological signals and activities have great potential in health monitoring and sports. However, fabricating sensors with a wide sensing range, high sensitivity, robustness, and the capability for seamless integration into apparel remains challenging. In this work, a textile resistive strain sensor (TRSS) fabricated by selectively inlaying a conductive yarn, that is covered with water-repellent and antioxidative acrylic/copper complex fibers, into a highly elastic substrate via an industrialized knitting process is proposed. The conductive yarn is folded and compactly stacked to sense strains by changing contact resistance through contact separation of adjacent yarn sections in stretching. Owing to this folded structure, the TRSS has a wide sensing range (0–70%), high sensitivity (maximum gauge factor GFmax = 1560), low detection limit (< 0.5%), long-term fatigue resistance over 4000 cycles, and it can be seamlessly integrated into and become a part of various smart apparel products. An elbow sleeve, a knee sleeve and a sock are demonstrated to effectively monitor and distinguish various human bending motions. The fabrication strategy paves a viable way for customizing high-performance strain sensors for developing novel wearable electronics and smart clothing to detect multimode human motions.