High-efficient conversion of the waste biomass into eco-friendly novel bifunctional materials for selective monitoring and effective removal of mercury ions (Hg2+) is of great significance to achieve the environment sustainable development, but has not attracted enough attention. Herein, we exploited glutathione (GSH) assisting waste tobacco leaf as the biomass-related precursors to successfully yield a novel red fluorescence emission biomass-based carbon nanodots (CDs) with a remarkably large Stokes shift of similar to 232 nm through one -pot hydrothermal method. Owing to the synergistic Hg-S bond and the coordination effects of the Hg2+ to the abundant -COOH, -NH2 and -OH groups on the surface of CDs, this proposed biomass-based CDs showed a red fluorescence decrease response for Hg2+ with a high selectivity and a lower detection limit of 0.45 mu M in environmental water samples. Furthermore, this binding endowed this proposed biomass-based CDs possessed a high removal efficiency of above 99.4% for Hg2+ as well. This work showed a novel insight into recycling the waste tobacco leaf into novel, economic, efficient, reliable, and eco-friendly biomass-based CDs for simulta-neously precise traceability and high-efficient removal of Hg2+ pollution in environmental matrices.