Simple structure and high sensitivity with a broad detection range are highly desirable for temperature sensor. This work presents a highly sensitive plasmonic sensor based on D-shaped photonic crystal fiber (PCF) in the near infrared region (900–1900 nm) for temperature measurement. The proposed sensor is designed by finite element method (FEM) based simulation tool and sensing properties are investigated by means of wavelength interrogation method (WIM). To support the surface plasmon oscillation, 45 nm gold film is deposited on the flat portion of the D-shaped PCF which consists of pure silica. Benzene is used as the temperature sensitive material that offers large propagation loss (PL) peak shift. Simulation outcome shows that the maximum possible sensitivity of 110 nm/°C in the temperature range from 10 °C to 70 °C. To our knowledge, the achieved sensitivity is the highest for temperature sensing in the existing literature. In addition, the proposed sensor exhibits the maximum figure of merit (FOM) of 5.5/°C, resolution of 9.09 × 10−4 °C, and excellent fitting characteristics of PL peak wavelengths. Moreover, low PL of the proposed sensor helps to extend the sensor length up to few centimeters. Such excellent results and wider temperature range make sure that the proposed sensor can be an appropriate choice for temperature measurement even in the remote sensing application.