<p>In this work, a new bionanosorbent of graphene oxide (GO) and <i>Dunaliella salina</i> (DS) microalgae was synthesized and applied for the adsorption and removal of malachite green (MG) from water and wastewater samples. The bionanosorbent (GO@DS) ​​was characterized by Fourier transform infrared spectroscopy, zero charge point, scanning electron microscopy coupled to an energy dispersive X-ray detector, and X-ray diffraction. Using multivariate optimization and response surface methodology, the optimal adsorption variables were pH = 5, GO@DS ​​mass = 5 mg, and malachite green concentration = 75 mg L⁻¹, for which an adsorption capacity of 232.77 mg g⁻¹ was obtained. Experimental kinetic results were adequately fit to the Elovich model. The Langmuir equilibrium model satisfactorily described the data obtained and a maximum adsorption capacity of 160.8 mg g⁻¹ was obtained. The adsorption process was thermodynamically favorable, spontaneous, and exothermic. Finally, the GO@DS ​​was applied to remove the dye from natural water and effluents, obtaining MG removal values ​​between 85 and 99%, demonstrating the efficiency of the bionanosorbent in real and complex matrices.</p>