This article reviews the most recent advances in the development of flexible substrates used as surface-enhanced Ra-man scattering (SERS) platforms for detecting several hazardous materials (e.g., explosives, pesticides, drugs, and dyes). Different flexible platforms such as papers/filter papers, fabrics, polymer nanofibers, and cellulose fibers have been investigated over the last few years and their SERS efficacies have been evaluated. We start with an introduction of the importance of hazardous materials trace detection followed by a summary of different SERS methodologies with par-ticular attention on flexible substrates and their advantages over the nanostructures and nanoparticle-based solid/hybrid substrates. The potential of flexible SERS substrates, in conjunction with a simple portable Raman spectrometer, is the power to enable practical/on-field/point of interest applications primarily because of their low-cost and easy sampling.