Flow-induced vibrations (FIVs) serve as the fundamental principle of non-rotary wind energy harvesting. However, nanogenerators relying on a single FIV effect remain constrained by insufficient breeze energy conversion efficiency. In this paper, we propose a novel galloping-flutter coupled nanogenerator (GFNG) that leverages the synergistic interaction between these two aerodynamic phenomena, to achieve high performance across broad wind speed bandwidth. A galloping-flutter coupled mechanism (GFM) is implemented using a multifunctional flexible beam that integrates a galloping piezoelectric energy harvester (GPEH) and a fluttering triboelectric nanogenerator (FTENG). Through meticulous optimization, it significantly enhances the average electrical output of the FTENG by up to six times at low wind speeds below 6 m s−1, by intensifying the triboelectric contact behavior through galloping-induced beam oscillations. The GFNG demonstrates a maximum average power of 6.3 mW across wind speeds from 1.4 to 10 m s−1, along with a remarkable power density of 7.1 W m−2 of the enhanced FTENG at 10 m s−1, enabling the lighting of 508 LEDs and stable power supply for wireless sensor nodes (WSNs). This study offers new insights into designing high-performance aerodynamics-driven nanogenerators by harnessing multiple FIV synergistic effects, broadening the potential for intelligent wind energy applications.