In this research, an ultra-high sensitive multimode interference-based fiber-optic temperature sensor is unveiled by radiating with a Vortex beam. The efficient excitation of several high-order modes within the waveguide structure has been affirmed by using the classical wave-optic model. By exploiting the advantages of Vortex beam, the difference in transmitted output power is determined for various surrounding temperatures, ranging from 28 °C–100 °C. To corroborate our theoretical study, an Eigenmode expansion solver (EME) propagation analysis has been carried out in commercially offered Mode solution software (Lumerical Inc.) to investigate the propagation characteristics of Vortex beam inside the waveguide structure. Our simulation outcome reflects a maximal temperature sensitivity of 0.14 dB/°C with a commendable sensing resolution of ∼0.07 °C. When compared to the conventional Gaussian beam-based sensor, such sensitivity of the proposed temperature sensor was found to be enhanced by a factor of about 3.5. Finally, we presented the systematic study describing the impact of fiber radius, order of Vortex beam, and waist size of input field on the sensor response. On account of such superior sensing performance, the proposed idea expedites new possibilities in any sort of physical, chemical or biological sensing needs.