Utilization of MSWI fly ash and corncob by combining fly ash and corncobs with a 1:10 ratio, activated with 75% KOH as an adsorbent to reduce methylene blue dye in textile wastewater. For the characterization testing of FACC, SEM-EDS, and pHpzc were used to determine the morphological conditions and pH value when FACC is in zero charged condition. Characterization results show that FACC has a rough surface and many pores with O, C, and K as dominant elements. pHpzc test shows that FACC will have a zero charge at pH 13.18. Experiments were conducted with batch method on the effect of adsorption operational parameters at contact time (0-120 min), FACC dosage (0.05-0.5 g/L), pollutant concentration (50-250 mg/L), and initial pH (2-10). Maximum removal efficiency was obtained at a contact time of 60 minutes, with a dosage of 0.5 g/L, pollutant concentration of 50 mg/L, and initial pH of 4 with a removal % of 98.37%. The Langmuir isotherm model described the adsorption mechanism with the maximum adsorption capacity reaching 344.828 mg/g. The adsorption rate used a pseudo-second-order kinetics model with a K2 value of 13.9 × 10−3 g/mg.min. FACC are good adsorbent alternatives for removing dyes in industrial wastewater.