<p>The effective suppression of low-frequency vibrations is essential for ensuring the safety and stability of engineering structures and mechanical systems. However, conventional structures exhibit inherent limitations in achieving broadband low-frequency vibration control. In this paper, an inerter-based metamaterial beam with active feedback control is proposed to achieve broadband vibration suppression in the low-frequency range. The dynamic equations of the proposed structural oscillator are formulated, and the system transfer function is derived by Laplace transform, with the necessary and sufficient conditions for system stability being established. Unlike conventional metamaterials, the proposed metamaterial structure incorporates an inerter element and an active feedback control mechanism. By considering the effect of feedback control, the dispersion relation of the system is analytically derived, and the influence of several key parameters and combinations on the bandgap characteristics is investigated. Compared with conventional metamaterial beams, we found that the frequency ranges of the bandgap could be broadened using feedback control. The accuracy of the theoretical band structure is validated by numerical simulations of the frequency response and dispersion curves. The results demonstrate that the proposed metamaterial beam exhibits marked improvements in low-frequency and broadband performance: the bandgap cut-on frequency is reduced by 17.6%, and the total bandgap width is enlarged by 39%, thereby enabling more effective broadband vibration suppression. This study may provide some insights into designing and optimizing metamaterials with enhanced vibration-attenuation capabilities.</p>