Stretchable and flexible strain sensors are essential components for next-generation wearable devices and human–machine interfaces. Among various approaches, piezo-transmittance-based strain sensors offer fast response and environmental stability.However, achieving both high sensitivity and precise directional decoupling remains a significant challenge. While sensors relying on random microcracks exhibit high gauge factors, their stochastic nature hinders axis-specific sensing. On the other hand, engineered macroscopic structures like metamaterials provide structural predictability, yet they often suffer from reduced sensitivity and notable mechanical crosstalk between orthogonal axes.In this study, a direction-aware piezo-transmittance strain sensor was developed by engineering a controlled linear gap-opening mechanism in an aligned carbon nanotubes (CNTs)/polydimethylsiloxane (PDMS) composite.The uniform gap-opening structure overcomes the limitations of traditional crack-based sensors, achieving enhanced directionality, high sensitivity (gauge factor $\approx$ 283), low detection limit (0.03%), and excellent sensor-to-sensor uniformity (relative standard deviation < 12%). The sensor exhibits reliable performance over 5,000 strain cycles and enables precise multi-directional strain sensing through sensor arrays that quantitatively decouple orthogonal strain components.Finally, the developed sensor was integrated into wearable platforms, including attachment to joints and incorporation into stretchable exercise bands, demonstrating its potential for real-time human motion monitoring and for integration into wearable fitness and rehabilitation devices.