The present work aims to study the radiation shielding parameters of new composite nickel ferrites in micro and nano-size. Synthesis of nickel-nano ferrites was carried out using the chemical co-precipitation technique. The measurement of gamma shielding parameters for nano-sized nickel ferrites was done experimentally. In addition, the calculations of the shielding parameters for the micro-sized nickel ferrites were carried out using FLUKA-Monte Carlo and WinXCom software. The shielding parameters were given in terms of mass and linear attenuation coefficients, half and tenth-value layer, mean free path, effective atomic number, and effective density of electrons values. Besides, the build-up factor and its parameters were calculated for the proposed shielding material. Fast neutrons effective removal cross-sections were also estimated for the NiCoFe2O4 composite at different Ni/Co ratios. It was found that the highest nickel content (W4), the best gamma radiation attenuation parameters for the proposed composite, with a slight difference between nano and micro-sized samples. The maximum obtained value of mass attenuation coefficient at 661.7 keV was 0.0753 and 0.0751 (cm2/g) for nano- and micro-sized ferrite samples. Furthermore, the highest fast neutron removal cross-section was 0.1562 cm−1 which was achieved with the highest cobalt content sample (W1).