The increasing demand for sustainable, rapid, and label-free sensing technologies in precision agriculture has driven the development of biodegradable alternatives to conventional sensors. In this study, we present a SERS platform based on ethyl cellulose, a renewable and solvent-processable substrate, functionalized with gold-coated MgFe hydrotalcite nanoplatelets for detecting cypermethrin, a common pyrethroid pesticide. The performance of the cellulose-based sensor was compared to a silicon-based counterpart. Despite its biodegradable nature, the ethyl cellulose sensor achieved a comparable limit of detection (1.6 μM vs. 1.3 μM), demonstrating its potential as a high-performance, eco-friendly alternative for Raman sensing applications.