Barocaloric effect in polymers is barely recognized and limited to a few reports in the literature. This effect consists of a thermal response of the material when a hydrostatic pressure is applied, allowing its application in the field of solid-state cooling. In this study, the barocaloric effect was investigated for a commercial polyurethane rubber (PU) subjected to three heat treatment temperatures (60, 100, and 115 °C) for 16 h to assess the limiting condition for this application. PU presents giant barocaloric effect, reaching adiabatic temperature change between 13 and 15 °C at a maximum pressure variation of 218 MPa, obtained under direct measurement, reaching a normalized refrigerant capacity of 11.07 kJ kg−1 GPa−1 (ΔTh-c = 25 °C, Δp = 174 MPa). Using the obtained data, it was possible to propose a quadratic model to predict the value of the adiabatic temperature variation as a function of the temperature and pressure applied in the PU. The PU characterization included differential scanning calorimetry and mechanical properties. The results obtained indicate a promising research field for the barocaloric effect in rubber polyurethanes.