Triboelectric nanogenerators (TENGs) have proven to be potential candidates for low-frequency vibration mechanical energy harvesting, which utilize different electron affinities material. In this regard, strong electron-donating tendencies materials are highly required to improve the TENGs’ performance. Here, a poly(diallyldimethylammonium chloride) (poly-DADMAC)/nylon-11 composite nanofibrous mat is newly proposed as a highly positive triboelectric layer for boosting the TENGs’ performance. Through the dielectric modulation of the nylon-11 nanofiber achieved by incorporating cationic poly-DADMAC, the output performance of the TENG was significantly enhanced by the relative dielectric constant, which is attributed to the three-fold increase in the surface charge trapping capability of the composite materials. After the incorporation of poly-DADMAC, the mechanical strength of the developed composite materials was six times greater than that of pristine nylon-11. The fabricated TENG showed excellent power density (7.6 W/m2) and sustainable power generation for low-power electronic devices. The proposed TENG was successfully demonstrated as a self-powered pressure sensor with an ultra-high sensitivity of 1.01 V/KPa. Furthermore, the TENG was utilized as a self-powered motion sensor for monitoring real-time human motion, including slow walking, fast walking, jogging, slow running, fast running, and jumping. Finally, the TENG was adopted and demonstrated to successfully monitor human motion status using a smartphone web application in the Internet of Things (IoT). These results of this study are expected to provide guidance for the construction of high-performance TENGs and promote the development of self-sustainable portable or wearable electronics and self-powered sensors.