The synthesis and characterization of gadolinium-based micro- and nanophosphors are reported. These materials were synthesized by solvent evaporation technique and microwave-assisted solvothermal method, respectively. According to scanning electron microscopy measurements, Gd₂O₃ and Gd(OH)₃ phosphors have lamellar and nanorods structures, respectively. Their luminescent properties are generated by the presence of Tb^3  + ions, which produced light emission at 484, 542, 583, and 621 nm due to the D₄5  →  F₆7, F₅7, F₄7, and F₃7 interlevel transitions within Tb^3  + electronic energy states. These phosphors were embedded into two polymers, polymethyl methacrylate and polystyrene, and their luminescent properties were transferred to polymeric films. In addition, in this case, films can be activated under lower excitation energy than powder phosphors because an energy transfer from polymers to Tb^3  + ions exists. The obtained results reveal that gadolinium-based micro- and nanophosphors are candidates for manufacturing luminescent materials in industrial and biological applications as well.