The development of flexible and stretchable electronics has attracted intensive attention for their promising applications in next-generation wearable functional devices. However, these stretchable devices that are made in a conventional planar format have largely hindered their development, especially in highly stretchable conditions. Herein, a novel type of highly stretchable, fiber-based triboelectric nanogenerator (fiber-like TENG) for power generation is developed. Owing to the advanced structural designs, including the fiber-convolving fiber and the stretchable electrodes on elastic silicone rubber fiber, the fiber-like TENG can be operated at stretching mode with high strains up to 70% and is demonstrated for a broad range of applications such as powering a commercial capacitor, LCD screen, digital watch/calculator, and self-powered acceleration sensor. This work verifies the promising potential of a novel fiber-based structure for both power generation and self-powered sensing.