In this paper, the potential capability of a novel dielectric modulated dual material gate nanowire junctionless MOSFET as a promising biosensor is demonstrated. The impact of the structural parameters on the sensitivity of the proposed device is thoroughly implemented for designing a low power, highly responsive biosensor. A nanogap is embedded in the gate insulator region for immobilizing the biomolecules. Accumulation of biomolecules in the nanogap changes the gate capacitance and results in threshold voltage deviation. The sensitivity of the biosensor can be improved for a wide range of biomolecules by adjusting the gate workfunction difference over the nanogap region and the remnant part of the channel. An optimum value of 0.5 eV difference is achieved. It is shown that by considering maximum length for the nanogap beside occupation of the whole volume of the cavity, a maximum degree of sensitivity for the biosensor can be achieved. In addition, there exists a tradeoff between the off-state current and sensitivity of the biosensor. Consequently, an optimum value of (3–5) × 10¹⁸ cm⁻³ is attained for the doping concentration. Moreover, absorption of negatively and positively charged biomolecules on the sensitivity of the sensor is discussed extensively. The results in this paper pave the way for integrating biodetection techniques with the existing CMOS technology.