<p>A chemical vapor deposition strategy is reported to develop a simple and efficient carbon oxide cloth (OCC)/MoS₂ flexible SERS substrate with acid-treated OCC as the deposition substrate, capable of detecting Rhodamine 6G concentrations as low as 1.0 × 10^− 12 M. By combining experimental analysis and density functional theory calculations, we found that the charge transfer between acid-treated carbon cloth and adsorbed molecules is enhanced because of its abundant oxygen-containing functional groups. More significantly, the flexible OCC/MoS₂ substrate enables the in-situ detection and efficient on-site photocatalytic degradation of organic contaminant residues on fish surfaces and in aquatic environments through simple swabbing or immersion sampling. Moreover, the flexible matrix exhibits excellent recyclability in both practical detection and photocatalysis applications.</p> Graphical Abstract <p></p>