Ti3C2Tx MXene's weak ability to capture negative triboelectric charges severely limits its application as a dielectric layer filler in triboelectric nanogenerators (TENGs). In this work, fluorinated MXene nanosheets (F-MXene) is successfully prepared by grafting perfluorocarbon chains onto the surface terminators of Ti3C2Tx MXene nanosheets through Fischer esterification reaction, using the carboxyl group of perfluorooctanoic acid (PFOA) as the active site, greatly enhancing its triboelectric charge capture capability. The F-MXene nanosheets are then used as dielectric filler materials, combined with biocompatible Ecoflex silicone rubber and spin-coated onto a conductive silver fiber electrode to construct a multifunctional triboelectric nanogenerator (FM-TENG) with continuous and stable output performance. Under realistic conditions of 35 °C and 83% relative humidity, the FM-TENG achieves 146% voltage output, 142% current output, 179% charge transfer compared to the TENG with Ti3C2Tx MXene nanosheets as the dielectric filler (SR-MXene TENG) and 363 mW m−2 power density. This self-powered system enables applications such as hand motion monitoring, letter recognition, and non-contact distance detection. This study demonstrates that improving the negative triboelectric charge capture capability of MXene nanosheets through perfluorocarbon chain modification provides a new strategy for enhancing the negative charge capture capability, thereby enabling the efficient and stable operation of triboelectric sensors.