This study presents a chiral mechanical metamaterial (CMM) designed to achieve broadband vibration attenuation and energy harvesting across all polarizations of elastic waves at low frequencies. The CMM is developed through a systematic approach, including theoretical eigenfrequency analysis and numerical simulations, to create a complete bandgap and defect structure. The defect structure is designed to induce defect modes for all wave polarizations within the bandgap region, ensuring compatibility with the overall structure. The proposed CMM with a defect (CMMD) demonstrates significant performance improvements, achieving electrical output power enhancements of 20.5 times for flexural waves and 511.4 times for longitudinal-torsional waves compared to the defectless CMM. The study highlights the potential of chiral mechanical metamaterials in applications such as energy harvesting, structural health monitoring, and wireless communications. Experimental validation confirms the effectiveness of the CMMD in both wave attenuation and energy harvesting, making it a versatile solution for various mechanical systems.This study presents a chiral mechanical metamaterial (CMM) designed to achieve broadband vibration attenuation and energy harvesting across all polarizations of elastic waves at low frequencies. The CMM is developed through a systematic approach, including theoretical eigenfrequency analysis and numerical simulations, to create a complete bandgap and defect structure. The defect structure is designed to induce defect modes for all wave polarizations within the bandgap region, ensuring compatibility with the overall structure. The proposed CMM with a defect (CMMD) demonstrates significant performance improvements, achieving electrical output power enhancements of 20.5 times for flexural waves and 511.4 times for longitudinal-torsional waves compared to the defectless CMM. The study highlights the potential of chiral mechanical metamaterials in applications such as energy harvesting, structural health monitoring, and wireless communications. Experimental validation confirms the effectiveness of the CMMD in both wave attenuation and energy harvesting, making it a versatile solution for various mechanical systems.