In the prosthetic field, quantifying interfacial pressure distribution between the amputee's residual limb and the socket’s internal environment is imperative for developing new technologies. However, the commercially available pressure sensors have several disadvantages, namely external power supply requirements, low stability, high cost, and complexities related to integrating the sensor system into prosthetic devices. Herein, we propose a self-powered triboelectric nanogenerator (TENG) based flexible tactile sensor array system to monitor prosthetic socket internal pressure distribution in real-time. The proposed sensor consists of biocompatible polydimethylsiloxane (PDMS) polymer and polycaprolactone (PCL) nanofiber membranes as triboelectric materials. The biodegradable PCL nanofiber membrane, fabricated via a scalable and cost-effective electrospinning process, possesses a high surface area-to-volume ratio, facilitating enhanced charge generation during triboelectrification. The as-fabricated TENG-based tactile sensor is highly stable up to 10,000 cycles. Furthermore, the voltage of the tactile sensor is independent of different temperature and humidity values, demonstrating the stability of the sensor under various environmental conditions. Finally, we successfully integrated the tactile sensor array within a prosthetic device to monitor real-time pressure distribution inside the prosthetic socket during gait simulation. We believe that the proposed novel design provides a new dimension for the rapid development of self-powered, low-cost, and highly stable pressure monitoring systems with considerable potential for commercialization.