The Microwave-Assisted Pyrolysis (MAP) method has the potential to be applied for the synthesis of dye adsorbents. In this work, the activated carbon (AC) was synthesized from the paper waste by the MAP method. The deinking paper waste was carbonized and activated using microwave heating with a frequency of 2.45 GHz and various power outputs (450, 600, and 800 W). The activation was carried out using ZnCl2 solution as an activating reagent. The impregnation with ZnCl2 is expected to give a clearer porous structure by absorbing microwave heat from inside and outside at the same time. The heating rate during the activation process can reach 211°C/min, which shows that the MAP method has the potential to provide a faster heating rate and shorter processing time compared to the furnace pyrolysis. The effect of the synthesis parameter such as impregnation ratio, time, and radiation power was studied from the adsorption efficiency on methylene blue (MB) dye. The activated carbon was characterized using the proximate test, SEM, and XRD. Best Result of the MAP method was obtained with a ratio of 1:1 (ZnCl2: Carbon) within 5 minutes of radiating, power of 800 W, with the results that AC can adsorb MB solution up to 2100 ppm with a maximum adsorption capacity of 1036.3 mg/g, and the efficiency of 99.87%.