The large-scale production of various synthetic dyes has significantly contributed to the discharge of large volumes of wastewater into the environment. It is estimated that approximately 105,000 tons of dyes from the textile industry are released annually, severely compromising water quality [1]. In this context, the present study evaluates the adsorption potential of agricultural and timber residues—including Tectona grandis sawdust, baobab sawdust, coconut shells, cork bark, almond shells, and olive pits—for the removal of methylene blue (MB) from aqueous solutions. All materials were used without prior thermal treatment. Kinetic experiments were carried out at 298 K and pH 6, using 25.0 mg of adsorbent added to 25.0 mL of MB solution (20 mg L⁻¹), agitated at 20 rpm for up to 168 hours. Adsorption isotherms were obtained using MB concentrations ranging from 0 to 250 mg L⁻¹, with agitation under the same conditions for 24 hours. The influence of pH (3–11) was assessed by adjusting the pH with 0.1 mol L⁻¹ HCl or NaOH and following the same adsorption procedure. The natural adsorbents demonstrated good performance in removing methylene blue from aqueous solutions. Among the tested agricultural wastes, coconut shells exhibited the highest MB removal capacity, reaching a maximum of 106 mg g⁻¹ at 298 K and pH 6. These findings support the use of agricultural and timber sector residues as efficient and sustainable alternatives to conventional materials such as activated carbons. This approach aligns with circular economy principles, promoting waste valorization and reducing environmental impacts.