The utilization of nanoporous materials is an extremely effective approach to enhance the electrical performance of triboelectric nanogenerators (TENGs). However, existing methods for preparing nanoporous tribo-materials are not only complicated, costly and time-consuming, but also waste a lot of material. Meanwhile, fabricated nanoporous tribo-materials that have low roughness by nature possess poor surface hydrophobicity, causing low output stability in humid environments. Here, a bio-inspired petiole-like micron fiber-based tribo-material with inner nanopores, rough surface nanostructures and superhydrophobicity is first designed that uses an extraordinarily simple, ultralow-waste and efficient single-component electrospinning process. The petiole-like structures and superhydrophobicity endow the assembled triboelectric nanogenerator (PMF-TENG) with outstanding electrical performance and superior output stability under humid conditions. With a giant power density of 56.9 W m-2 and a high peak-to-peak output voltage of 2209 V, the optimized PMF-TENG can not only be used as a biomechanical energy harvester to directly drive 833 light-emitting-diodes and small electronics, but also serve as a self-powered sensor to detect body motions. Moreover, under a high relative humidity of 80%, the output retention rate of the optimized PMF-TENG is 1.7 and 2.2 times higher than the TENG assembled with the traditional smoother solid nanofiber-based tribo-material and the monolithic nanoporous tribo-material-based TENG, respectively. This work provides an easy-to-fabricate high-performance nanoporous material-based TENG with ultralow material waste and extends its potential for application in humid conditions.