The fabrication of the nanostructures required for surface-enhanced Raman scattering (SERS), which is increasingly used for chemical analysis, is complex and expensive. We demonstrated the feasibility of using low-cost, flexible SERS substrates produced using melt-blown nonwoven polypropylene (PP) fabrics as the base material. First, nonwoven PP fabrics with fiber diameters of 5.7 ± 3.3 µm were prepared using the melt-blowing method. These fabrics were then hydrophilized using plasma treatment and densely modified with Ag nanoparticles with a diameter of approximately 90 nm by electroless plating involving a sensitization-activation process and the reduction of AgNO3. The SERS response of the Raman probe, 4-aminothiophenol (4-ATP), indicated that the resulting PP SERS substrates were more sensitive than a commercial low-cost SERS substrate made of laser nanopatterned soda lime glass coated with Ag in the concentration range of 10−4–10−6 M. The responses for 10−3 M 4-ATP after 3, 7, and 14 d were 103.0, 104.6, and 86.7%, respectively, based on the Raman peak at 1140 cm−1 measured on the day after fabrication (1 d). Thus, the fabricated PP SERS substrates are suitable for use as low-cost and flexible SERS substrates for chemical analysis.