This study developed and evaluated a dual-material gate stack double-gate FinFET-based biosensor (DM-GS-DG FinFET). The device was dielectrically modulated and investigated for molecules, such as streptavidin, gluten, zein, hen egg-white lysozyme, and acetylene tetrabromide, based on current, threshold voltage, subthreshold swing, and switching sensitivity. The influence of charged and neutral biomolecules within the nanocavity on the electric, analog, and radiofrequency parameters was recorded. This study was conducted relative to different dielectric κ-values of 12 in terms of the percentage sensitivity improvement (SI%). The results reveal that the percentage of sensitivity ION improves effectively, especially for low κ-values, compared with other sensitivity measures. All the sensitivity evaluations indicated that DM-GS-DG-FinFET combined with biomolecules is a viable option for biosensing purposes.