This research explores the potential of vortex-induced vibration (VIV) as a viable renewable energy source for harvesting low-speed wind energy, particularly for low-power sensors utilized in structural health monitoring. By integrating experimental methods, mathematical modelling through the wake oscillator model, and computational fluid dynamics (CFD) simulations, we present a holistic examination of fluid-structure interaction (FSI) in the context of energy generation. The experimental phase involved an elastically mounted circular cylinder positioned on an aluminium beam inside a wind tunnel, where the Reynolds number varied from 4,100 to 11,500. The cylinder's motion was limited to the transverse direction, leading to significant findings within the lock-in region—characterized by the highest amplitudes of vibration and, correspondingly, the greatest power output. Our data indicated that increased oscillation amplitudes enhanced piezoelectric voltage and power output, primarily due to increased strain within the piezoelectric layers. The peak output voltage was recorded at a reduced velocity (Ur) of 5.7, while the optimal load resistance for energy extraction was determined to be 6.56 MΩ based on repeated experimental trials. Mathematical modelling was then implemented, bringing a deeper phenomenological understanding through the wake oscillator model, which could effectively explain the lock-in range and amplitude of experimental data. Moreover, numerical simulations utilizing the SST k–ω turbulence model further contributed insights into the vortex dynamics behind the cylinder and their response to varying flow speeds.