Nanocomposites offer a wide range of applications and have the potential to revolutionize various industries. Through carefully selection of the matrix material and nanoparticles, it becomes possible to fabricate materials that possess customized properties, hence, tailoring to specific needs and efficiently addressing challenges encountered in various applications. Zinc oxide (ZnO), strontium ferrite (SrFe12O19), and their nanocomposites ZnO/xSFO (x = 1%, 3%, and 5%) have been synthesized using the co-precipitation method. X-ray diffraction assures the crystal structure of ZnO, SFO, and their nanocomposites, with crystallite size of 27 nm for ZnO and 41 nm for nanocomposites. High-resolution transmission electron analysis shows the semi-spherical agglomerated polycrystalline particles with particle size 25 nm, 9 nm, and 47 nm for ZnO, SFO, and ZnO/5%SFO, respectively. The dielectric characteristics and ac conductivity were examined as a function of frequency (4–8 MHz) and at different temperatures ranging from 30 to 180 °C. The results obtained at room temperature show the dielectric constant, dielectric loss factor, and ac conductivity are enhanced by increasing SFO content, reaching their peak at a concentration of 3% SFO. The mass attenuation coefficient of incident neutrons in the energy range from 10–5 eV to 20 MeV was studied to evaluate the ability of the prepared samples as neutron-shielding materials. SFO sample has higher neutron attenuation capability than other investigated samples. The study indicates that the total mass attenuation coefficient in the 1 eV to 1 MeV neutron energy range primarily results from elastic interactions for all materials under investigation. The results indicate that higher SFO concentrations in ZnO result in a slight increase in absorption at low energies and in elastic scattering at higher energies. Furthermore, the results indicated that the attenuation coefficient of the samples for fast neutrons in the range of 2 MeV to 12 MeV is ≈ 0.14 cm−1, a notably high value compared to many shielding materials reported in various literature.