A prevalent scenario in mechanical, civil, and aeronautical engineering involves flexural beams that support concentrated masses such as engines, motors, oscillators, or vibration absorbers mounted with elasticity. In the context of vibration dynamics and suppression within mechanical engineering and robotics, certain systems can be effectively modeled as a clamped-free beam with a tip mass connected to a spring-mass system. This paper presents a metastructure based on the Euler–Bernoulli beam theory. The metastructure comprises a cantilever beam linked to several rigid elastic vibration absorber models. The theoretical investigation, employing the spectral element method, delves into flexural wave propagation and vibration attenuation characteristics. The proposed metastructure exhibits a stop band in a lower frequency range than traditional spring-mass resonators, thanks to the inherent antiresonance phenomenon, allowing for a lower-frequency stop band. It also induces double anti-resonance drops, achieving a wider bandgap. Additionally, by adjusting the properties of the elastic beam and rigid masses, the location and bandwidth of flexural wave band gaps can be effectively tuned through system parameter modifications. This adaptability is beneficial for optimizing the broadband low-frequency flexural wave attenuation performance of the proposed rigid elastic beam-type metastructure.