In this study, mechanically alloyed Fe70Nb10V10B10, Co70Nb10V10B10, Ni70Nb10V10B10, and (FeCoNi) 70Nb10V10B10 high-entropy alloys were successfully synthesized, and their structural, magnetic, and radiation shielding properties were systematically investigated. Structural analysis revealed that Fe favored bcc phase formation, while Co and Ni stabilized fcc structures; the equiatomic alloy resulted in a single-phase fcc solid solution with the smallest crystallite size (2.1 nm). All samples exhibited soft ferromagnetic behavior, with the Fe-based alloy achieving the highest saturation magnetization (120 emu/g), and the (FeCoNi) 70Nb10V10B10 alloy displaying the lowest coercivity. Among all compositions, Co70Nb10V10B10 demonstrated the best gamma and neutron shielding performance, showing the highest linear attenuation coefficient and fast neutron removal cross-section. The equiatomic alloy also exhibited well-balanced and stable shielding behavior. These findings position Co70Nb10V10B10 as a promising candidate for multifunctional applications requiring both efficient radiation protection and favorable magnetic properties.