Stretchable and wearable strain sensors hold significant potential in human motion monitoring and health management, yet the mutual constraints between sensitivity and stretchability remain a critical challenge. This study proposes a multidimensional composite network structure based on MXene and silver nanoparticles (Ag NPs) to address the limited strain range caused by the close interlayer stacking and strong interaction forces in two-dimensional materials. By embedding Ag NPs into the interlayers of MXene, the interlayer spacing was significantly expanded, which weakened interlayer forces and facilitated effective slippage, thereby synergistically enhancing the sensor performance. Experimental results demonstrated that with 5 wt % Ag NPs doping, the sensor exhibited exceptional comprehensive performance: a sensitivity (gauge factor, GF) exceeding 153.28 across a strain range of 0–51.5%, a maximum detectable strain of 51.5%, a low detection limit of 0.025%, and robust cyclic stability over 5000 stretching cycles. Mechanistic studies revealed that Ag NPs suppressed crack propagation through a lubricating effect while increasing conductive contact points to enhance sensitivity. Furthermore, the sensor achieved real-time monitoring of human physiological signals (e.g., pulse, swallowing, and joint movements), highlighting its potential for wearable health monitoring. This work provides novel insights into optimizing the performance of two-dimensional materials in flexible electronic devices.