Plasmonic biosensors, which combine the optical intensification of plasmonic nanostructures with the electrical sensitivity of FETs, are a state-of-the-art development in biosensing. By introducing noble metals such as silver (Ag) or gold (Au), biomolecules can be detected with extreme sensitivity using a range of techniques, such as electrochemical transduction, Surface Enhanced Raman Scattering (SERS), and localized surface plasmon resonance (LSPR). These procedures’ real-time detection has uses in environmental monitoring, food safety, and medical diagnostics, among other fields. This chapter comprehensively reviews the state-of-the-art in plasmonic FET biosensors, focusing on their unique properties, innovative fabrication methods, such as material vapor (PVD) or atomic layer (ALD) deposition procedures, imprinting on nanostructures (NIL), and electron beam lithography (EBL), and transformative applications in medical diagnostics. Priorities for the upcoming years include low-cost manufacturing, AI-based biosensors, and microminiaturization to facilitate the transfer from the research stage to commercialization for environmental and medical precision monitoring.