At present, the nanostructures consisting of tungsten metal are hardly explored for surface plasmon resonance–based applications in sensing and other photonic devices. In this view, a plasmonic nanostructure consisting of stacked tungsten gratings on aluminum nitride substrate with nickel interlayer is proposed and simulated for refractive index (RI) sensing in the visible and near infrared spectral regions. Rigorous coupled wave analysis (RCWA) with p-polarized light source is used for simulation and analysis. The sodium chloride (NaCl) concentration in water and gaseous medium is considered analyte. The performance of proposed plasmonic sensor is demonstrated in terms of sensitivity, resolution, and figure-of-merit values. In addition, a detailed analysis is also performed to study the effect of grating variable values on the sensor’s performance. The angle of light incidence emerges as an important parameter in significantly enhancing the sensor’s performance as well as in tuning the sensor’s applicability as per available light source. Further, it is shown that the same probe can be applied as a gas sensor with high sensitivity and accuracy. Moreover, the prominent absorbance characteristics of the proposed nanostructure leads to possible applications in spectral filtering as well as photodetection in both visible and NIR spectral regions. Owing to the advanced properties of tungsten, the proposed structure will be beneficial for bio- and gas-sensing applications along with other photonic devices operable in a wide spectral range.