The preparation of a copper aluminum/biochar composite and its application for the adsorption of procion red dye was studied. The composite materials were prepared by a co-precipitation method and characterised by X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, and thermogravimetry. The results of the adsorption study show that adsorption on the copper aluminum/biochar composite follows pseudo-second-order kinetics, and the adsorption isotherm of procion red conforms to the Langmuir isotherm model. The Langmuir fitting result for the maximum adsorption quantity of procion red on copper aluminum/biochar composite is 175.439 mg/g, which is higher than copper aluminum layered double hydroxide. The thermodynamic analysis suggests that procion red adsorption is spontaneous (standard free energy < 0) and endothermic and involves a random solid–liquid phase interface. The composite materials exhibited good recycling performance.