The excess usage of herbicides for agricultural scale up has turned out as one of the biggest concerns in environmental safety. Therefore it is obligatory need in front of researchers to develop the fast and highly sensitive methodology for the recognition of herbicides. In this view, the current work proposed a novel fluorescent-turn off sensing label of Pr(III) doped Gd2O3 (Pr@Gd2O3) nanoparticles (NPs) for detecting one of the widely used herbicide i.e. 2,4-Dichlorophenoxyacetic acid (2,4 D) in aqueous media. Pr@Gd2O3 was synthesized by microwave assisted calcination process. The effect of percentage doping on porosity, optical, luminescence and thermal properties of Pr@Gd2O3 was well explained in this work. The fluorescence studies have shown that 5% doped Pr@ Gd2O3 displayed maximum emission intensity at 649 nm. In addition, out of 5%, 10% and 15% doped Pr@Gd2O3, 5% doped particles have displayed excellent fluorescence selectivity for 2,4 D over atrazine, imazapyr, glyphosate and OP. The calculations revealed that Pr@Gd2O3 NPs have the ability to sense 2,4 D in concentration ranging from 1 to 25 ppm with detection limit was 78 ppb under the optimum conditions. The recovery efficiency of 90-100% in real water samples has further supported the efficiency of prepared nano-labels for practical applications. (C) 2020 Elsevier B.V. All rights reserved.