Controlling impedance matching and enhancing absorption properties are crucial for developing next-generation microwave absorbing materials. Herein, we report the facile preparation of honeycomb-like core–shell nickel/copper silicate (Ni/CuSiO₃) composite nanospheres with controlled shell (CuSiO₃) thickness to control impedance matching and enhance absorption properties. The nanospheres with a shell thickness of about 30 nm had greatly improved microwave absorption performance. They exhibited a strong reflection loss of −39.5 dB (9.6 GHz) at the absorber thickness of 2.5 mm, with a wide effective absorbing bandwidth of 4.8 GHz (7.8–12.6 GHz). This remarkable microwave absorption performance is attributed to a novel structure that enhanced interfacial polarization and controlled shell thickness, resulting in good impedance matching of electromagnetic properties (ε, μ) and magnetic loss. Our permittivity-controlled core–shell Ni/CuSiO₃ composite nanospheres could be used to fabricate novel high-performance microwave absorbers.