The rubber fruit shell (RFS) activated carbon has been made using KOH as a chemical activating agent with several variations of the impregnation ratio (1:3, 1:4, and 1:5). To ascertain the impact of the impregnation ratio on the attributes of the produced activated carbon, analysis was carried out using thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) method, X-ray diffraction, and a field emission scanning electron microscope. In the impregnation ratio, 1:5 was carried out as the best result; the value for BET surface area and nitrogen adsorption isotherms were 160 m2/g and 62 cm3/g, where the average pore size diameter was 4.6 nm. Besides, this activated carbon also has around 78.40% carbon. According to the findings of this investigation, the impregnation ratio affects the performance of using KOH as an activator to produce activated carbon from rubber fruit shells. In addition, it could be indicated that the RFS has the potential to be an alternative source of relatively inexpensive activated carbon because the raw materials are available in large quantities.