[en] Highlights: • MWCNT/NiO-Fe₃O₄ heterotrimers are firstly successfully fabricated. • Significant interfacial polarization is generated. • Effective electromagnetic adsorption band covers a frequency range of 3.5–18 GHz. • Attenuating 75% electrical field and 50% magnetic field of 50 Hz power frequency is achieved. Severe electromagnetic (EM) interference pollution as the fourth pollution has posed an ever increasing threat to human health and environment. These dangers have created an urgent need for the development of EM absorbers to address this issue. Herein, nanosized NiO and Fe₃O₄ particles were decorated along multiwalled carbon nanotubes (MWCNT) to achieve high-performance attenuation of EM waves of 2–18 GHz and a power frequency of 50 Hz. The hybrid nanotubes were prepared by an electroless nickel plating-oxidization process to form MWCNT/NiO, then followed by a polyol approach to produce triple-component MWCNT/NiO-Fe₃O₄ hybrid nanotubes. The microstructure of the hybrid was characterized by transmission electron microscopy, X-ray diffraction and vector network analysis. It was found that the multi-component structure endows the MWCNT/NiO-Fe₃O₄ hybrid nanotubes with an effective EM absorption band (RL < −10 dB) covering a frequency range of 3.5–18 GHz. As well, the MWCNT/NiO-Fe₃O₄ hybrid nanotubes had the ability to attenuate 75% of the electrical field and 50% of the magnetic field of a 50 Hz power frequency.