This paper describes a two-step method for preparing the bi-functional cobalt sulfide/noble metal CoS₂/Au (CoS/Au) composite with excellent peroxidase-like activity and surface enhanced Raman scattering (SERS) performance. CoS₂ (CoS) was firstly synthesized via a hydrothermal method and subsequently used to coat Au nanoparticles. Both of them have high-efficiency peroxidase-like activity to decompose H₂O₂ into hydroxyl radicals, which can degrade organic pollutants into small non-toxic molecules. Furthermore, these composites also exhibit SERS performance using rhodamine 6G as a molecular probe. Therefore, the bi-functional composites can be applied in degrading R6G molecules as a valid catalyst while the degradation process can be monitored quantitatively in real time using Raman spectroscopy.