We report the polarizing behavior of aligned Ni nanoparticles (NPs) having average diameter of 165±15 nm in ∼210 μm thick polyvinyl alcohol (PVA) matrix in the frequency range of 0.2–1.6 THz. The NPs have been prepared via a wet chemical route and then aligned in PVA film by using an external magnetic field. When the polarization of THz electric field is parallel to the NPs alignment direction, a strong THz absorption is observed whereas a minimum THz absorption is noticed for the corresponding perpendicular configuration. Degree of polarization is calculated to be 0.9±0.08. Considering the good polarizing performance, ease of preparation, durability, and low maintenance, this aligned NP system is a perfect candidate to emerge as a potential THz polarizer.