Abstract Dielectric Modulated (DM) biosensors are being developed for label-free biosensing based on varying dielectric constants of the cavity region. In this paper, we proposed a GaAs_1−xSb_x based cylindrical DM biosensor. The chosen device geometry provides enhanced gate control and increases cavity area compared to the planar devices. This bestows larger dwelling space to the biomolecules. In our work, we have investigated the sensing capability of the proposed biosensor for Biotin (k = 2.63), Bacteriophage (k = 6.3), and Gelatin (k = 12); whereas, the proposed study is applicable in all types of biomolecules which are characterized by the dielectric constants. The deviation in the effective oxide thickness (EOT) due to the variation in permittivity of the cavity area modulates the channel conductance and, in turn, ON current and threshold voltages (V_th). Thus, these parameters can be used for analyzing the sensitivity. For the gelatin biomolecule, the maximum computed sensitivity with regard to the OFF to ON current ratio and saturation current is 41.20% and 16.68%, respectively. Further, we also investigated the sensitivity metrics for the charge-carrying biomolecules using trap models employed in TCAD simulations.