Fiber-based triboelectric nanogenerators (TENGs) possess advantages of good air permeability, excellent mechanical compliance, and easy integration into electronic textiles, and have wide application prospects in new-generation wearable electronics. However, few studies show the capability to unite favorable merits of excellent stretchability, high electrical generation, and conversion of multiple mechanical stimuli into a single fiber device. Here, we proposed a helically structured fiber-based triboelectric nanogenerator (HS-TENG) using Ti3C2Tx as the triboelectric coating. The unique architecture endows the HS-TENG with large stretchability (~ 200 % strain), and high electric output (52 V, 1.5 µA, 4.2 μW) under compression for a 2 cm long device, superior to most stretchable triboelectric yarns. The HS-TENG also realizes multi-mode (i.e., stretch, press, twist, and bend) mechano-electrical conversion. The HS-TENG fiber can be integrated into electronic textiles (E-textiles) for versatile applications, including an insole for energy harvesting, a kneepad for motion sensing, and a glove for wireless signal control. This work provides new capabilities for multifunctional wearable systems.