<p>This research introduces the development of 5‐(4‐chlorophenyl)‐1‐(4‐sulphamoylphenyl)‐1H‐1,2,3‐triazole‐4‐carbothioamide (<b>2</b>) focusing on its selective metal ion affinity and biological activities. Compound <b>2</b> exhibited remarkable selectivity for Cu²⁺ ions, demonstrating a distinctive colour change (naked-eye detection), significant alterations in absorbance and emission spectra upon exposure to copper ions, and no such responses to other metal ions. Density functional theory (DFT) studies elucidated the binding mechanism, emphasizing electron transfer as crucial in facilitating coordinate bond formation between <b>2</b> and Cu²⁺ ions. Comparative studies with another derivative, 4‐[5‐(4‐chlorophenyl)‐4‐cyano‐1H‐1,2,3‐triazol‐1‐yl]benzenesulphonamide (<b>1</b>), underscore the importance of functional group having nitrogen and sulphur atoms in compound <b>2</b>’s skeleton as pivotal binding sites for Cu²⁺ ions. Compound <b>2</b> also displayed excellent antimicrobial activity (against Gram-positive and Gram-negative bacterial strains, and a fungal strain) and notable antioxidant activity. Calculated values of ADME parameters confirmed the favourable drug-likeness behaviour of <b>2</b>. Non-toxic nature of <b>2</b> proves it applicable for Cu²⁺ detection in systems, where both biocompatibility and sensing ability are required.</p> Graphical abstract <p>This research presents novel photophysical and biological applications of 5‐(4‐Chlorophenyl)‐1‐(4‐sulfamoylphenyl)‐1H‐1,2,3‐triazole‐4‐carbothioamide (2) as a chemosensor and antimicrobial as well as anti-oxidant agent, respectively. Compound 2 exhibited a distinct color change from colorless to yellow with Cu2+ ions, selectively. Further, compound 2 exhibited excellent inhibition potential against the growth of pathogenic microbes as well as free radicals.</p> <p></p>