The present study describes the development of an efficient electrochemical sensing platform based on gold-copper alloy nanoparticles (Au-Cu NPs) used for detection of nitro aromatic toxins. The redox behaviour of four nitro functional group containing aromatic compounds was studied on five different NPs based sensors by square wave and differential pulse voltammetric techniques. Under optimized conditions, these functional group containing aromatic compounds exhibited reduction peaks within the range of −785 mV to −881 mV (versus Ag/AgCl) at the alloy NPs based modified electrodes. The results revealed that Au-Cu (1:3) modified Glassy Carbon Electrode (Au-Cu(1:3)/GCE) exhibit ultrahigh-sensitivity for the detection of 2-amino-4-nitrophenol, 4-nitrophenol, 2-methyl-3-nitrophenyl acetic acid and 3-nitrotoulene. The performance of the developed method was further examined for the determination of 2-amino-4-nitrophenol in drinking and tap water samples. UV/Vis spectroscopy was performed to study the catalytic reduction of 2-amino-4-nitrophenol by using Au-Cu (1:3) NPs alloy. Computational studies were carried out in order to correlate experimental findings by theoretical outcomes. We expect that these results will let the chemists to apply such sensors for various metallic, organic and organometallic toxins with slight modification.