This study explored the transformation of cassava peels (Manihot esculenta) into activated carbon via chemical activation with phosphoric acid, and investigated by varying impregnation ratios and temperatures to optimize adsorption efficiency for diclofenac removal. It examined the feasibility of using cassava peels as precursors for activated carbon specifically for diclofenac removal.  Cassava peels were impregnated with phosphoric acid at a ratio of 1:1.5 and 1:2 followed by carbonization at 450 °C, 500 °C for 1 and 2 hours to convert organic matters into a carbon-rich residue. The parameter analysis was conducted to characterize the activated carbon samples, by assessing parameters such as yield, pH, moisture content, functional groups, and particle size. Subsequently, the carbonized samples were activated using an activating agent to enhance their adsorption properties from CPAC1 to CPAC8. The resulting activated carbon from cassava peels demonstrated the yields of activated carbona were 33.88%, 37.98%, 44.01%, 45.54%, 35.1%, 34.98%, 45.99% and 48.84%, respectively. The pH values of these activated carbons were 6.75, 6.78, 6.71, 6.78, 6.61, 6.75, 6.5 and 6.78, respectively. The moisture contents of activated carbons were 2.38%, 3.04%, 3.64%, 2.37%, 2.94%, 2.75%, 2.44% and 2.33%, respectively. Conversely, the selected three conditions based on characteristics of the activated carbon derived from cassava peels displayed corresponding percentages of removal efficiency of 84.32%, 90.46% and 91.35%, respectively. The study utilized a series of batch adsorption experiments to investigate the adsorption capacity, kinetics, and isotherms of produced activated carbons.The adsorption process was found to be highly dependent on contact time, initial concentration, and pH. The activated carbon exhibited a maximum adsorption capacity of 10 mg/g at optimal conditions. The adsorption data were best described by the Freundlich isotherm model, indicating a heterogeneous surface with a non-uniform distribution of heat of adsorption. Kinetic studies revealed that the adsorption followed a pseudo-second-order model, suggesting chemisorption as the rate-limiting step. These findings demonstrate the potential of cassava peels derived activated carbon as a cost-effective and sustainable adsorbent for the removal of Diclofenac contaminants from water.