Abstract: Wind-induced vibrations are a common occurrence in nature and have great potential as a viable energy source. Effectively harvesting energy from the structure’s large amplitude response caused by wind-induced vibrations can power microelectronic devices, however, it is still a significant challenge in the field of energy harvesting. In order to efficiently harvest wind-induced vibration energy, this paper proposes a magnetic sliding airfoil flutter energy harvester. A dynamic model of the harvester is established based on a semi-empirical nonlinear aerodynamic model and the electromechanical coupling coefficient related to the position of the magnets. An experimental prototype is created and a wind tunnel test platform is built. In the experiment, by increasing and decreasing the wind speed, two different initial states are provided for the harvester, and two cut-in wind speeds are discovered 5.2 m/s and 8.3 m/s. A sudden jump phenomenon occurs at 8.3 m/s in downward sweeping wind speed experiments. Two jump points and a multi-solution region are found at 6.8 m/s and 8.2 m/s in numerical simulations. The displacement response exhibits a sine waveform, while the output voltage shows a non-sinusoidal waveform with significant even-order harmonics. The simulated plunging displacement and voltage output waveform closely match the experimental waveform, confirming the accuracy of the model. The output root mean square voltage of the energy harvester increases with the increase of resistance, and the average power shows an increasing-then-decreasing trend with resistance. An analysis is conducted on the impact of load resistance on energy harvesting performance. At the wind speed of 8.6 m/s, the average power in the experiment reaches its maximum value of 7.5 mW when the load resistance is close to the coil’s resistance. Overal, this article provides a new design approach for efficient flutter-based energy harvesters, offering a reference for the design of other forms of wind-induced vibration energy harvesters such as galloping-induced and vortex-induced vibration.