In this work, the ConBr lectin was non-covalently immobilized onto hydrochar (HC). This carbonaceous material was produced by the hydrothermal carbonization of glucose and then put to interact with the lectin, aiming to immobilize the biomolecule via electrostatic interactions. Samples obtained after the interaction were characterized by CHNS elemental analysis, scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). FTIR results from the conjugated sample identified the presence of NH2+ and NH3+ groups of the protein and COO- groups of the HC, indicating the occurrence of electrostatic interaction between the biomolecule and the support. Furthermore, the immobilization experiment was also performed using ConBr lectin marked with fluorescein isothiocyanate to assess the immobilization on the hydrochar using fluorescence emission analysis. Hemagglutination tests revealed that even after the conjugation with the HC, the agglutinating property of lectin toward erythrocytes (red blood cells) was preserved. Finally, our results indicate that non-covalent interactions represent an efficient mechanism for protein immobilization on the HC while maintaining the protein structure and its biological activity.