Nanoporous green materials like nanozeolite has been in focus for their superb efficiency to treat industrial wastewater. The study reports ultrasound assisted hydrothermal method as a very fast method to convert industrial fly ash from different sources of eastern India to nanozeolite X for efficient removal of toxic dyes and metals from industrial effluent. The pure nanosized zeolite X was synthesized rapidly at 20 min of ultrasound treatment after alkali fusion. The efficiency of nanozeolite X was determined in terms of the adsorption capacity towards various divalent ions such as Zn2+, Cu2+, Cd2+, Pb2+, Ni2+, Ca2+, and Mg2+ as well as various dyes such as methylene blue, crystal violet, indigo carmine, and Congo red. In comparison to commercially available microporous Zeolite X (a maximum of 120.43 mg g−1 for Pb2+ and 134.62 mg g−1 by for methylene blue), all synthesized nanozeolite X shows high adsorption capacity for metals (a maximum of 196.24 mg g−1 for Pb2+) as well as dyes (193.45 mg g−1 for methylene blue). Highly pure nanozeolite X has shown immense potential for treatment of real time industrial wastewater.