Electrocoagulation was demonstrated for the effective removal of organic dyes, waxes, and sodium silicate from batik wastewater. For the first time, the reuse of an electrocoagulated batik sludge (EBS) by converting it into an adsorbent for Acid Red 18 (AR18) dye removal is reported. The EBS sample was dried in an oven to produce the raw EBS (REBS) adsorbent, which was then calcined to remove its organic constituents to give calcined EBS (CEBS) adsorbent. Nitrogen adsorption–desorption isotherm, scanning electron microscope-energy-dispersive X-ray (SEM–EDX), and Fourier transformed infrared (FTIR) analyses were applicable to reveal the adsorbents’ physical and chemical characteristics. Effect of different preparation methods (REBS and CEBS), initial solution pH (3–9), adsorbent dosage (0.1–0.4 g/200 mL), initial concentrations (25–100 mg/L), and temperature (30–50 °C) on the adsorption of AR18 dye as well as regeneration and leaching study of the adsorbent were elucidated. The isotherm results indicated that the experimental data were best fitted to the Langmuir model with maximum adsorption capacity, q_max of 51.62 mg/g. Meanwhile, the adsorption of AR18 dye onto REBS mainly occurred through chemisorption as the kinetic data were best described by the pseudo-second-order model. REBS appeared to be a potential adsorbent for the removal of AR18 dye due to its simple preparation method, good adsorption capacity, and reusability performance.