During past decade, the ternary nanocomposite is ubiquitous in nanotechnology. Herein, a simple fabrication of cuprous oxide (cu 2 O) and silver (Ag) nanoparticles into Tetraaniline (TANI) matrix by in situ-polymerization approach to attain Tetramer-Metal Oxide-Metal (TANI/Cu 2 O/Ag, shortly TCA) ternary composite was reported firstly. The synthesized materials were further characterized by a series of instrumental techniques to understand its structure, morphology and thermal properties. This nanocomposite showed promising applications in wastewater treatment by the testing of photocatalytic activity over the pararosaniline hydrochloride (PRA) dye degradation under visible light radiations, removal of Cadmium ion (Cd 2+) by adsorption, corrosion resistance and antibacterial activity against both gram positive and gram negative bacterial strains. The obtained results of TCA compared with the pure TANI and binary nanocomposite (TANI/Cu 2 o) declared that the tcA composite is excellent material to solve the environmental issues due to lesser bandgap energy, visible light respond, high absorptivity, and long-life excitation. Water has exploit asset on the earth, as concern for human beings, the water pollution is currently great issue throughout world and cause copious diseases almost leads to death 1,2. In developing countries, the drinking water contamination by the second largest source mainly pesticides, chemical fertilizer residues and dyes are said to be concern agents 3. The nanomaterials have enormous potential to deletion of heavy metals, organic pollutants, inorganic anions and bacteria have been reported 4-7. Based on copious studies, the nanomaterials illustrate great importance for applications in purify the contaminated water. As a result of the small size, large surface area, especially high mobility in solution, the nanomaterials ensure strong adsorption capacities and reactivity 8. The nanomaterials exclusively metal oxide semiconductors have attracted by the scientists in evolving the pollute water treatment methods. Nanocatalysts (second class of nanomaterials) such as electrocatalysts, fenton based catalysts (photocatalysts) to developing for organic pollutants degradation and antimicrobial properties 9-11. The number of processes has been employed yet but they are ineffective and moreover time consuming. For example, adsorption process converts the dyes from one form to another. Later the Advanced Oxidation Processes (AOP) embraces Fenton, photo Fenton, ozonisation, semiconductor based photocatalysis, photolysis have been developed for the effective decolouration of dye pollutants and destroy the microorganisms. In photocatalysis, the water and oxygen undergo redox reactions which produce extremely Reactive Oxygen Species (*OH, *O 2 −) which are most accountable for the dyes degradation under light illumination 12. Especially the semiconductor heterogeneous photocatalysis seems as better destructive technology to the total decolouration of dyes and destroy the microorganisms. Cuprous oxide (Cu 2...