Model for Urban Storm Water Improvement Conceptualism (MUSIC) software has been widely used to predict the treatment and performance of stormwater Best Management Practices (BMPs) such as bioretention for decision-making purposes in stormwater management. However, the calibration of bioretention models based on pollutant runoff characteristics in the tropics is rarely studied. This paper presents the calibration of bioretention model parameters using MUSIC software to treat polluted runoff in a tropical climate. The bioretention model was simulated based on a pilot study at the Universiti Sains Malaysia (USM) engineering campus to evaluate the flow rate and pollutant’s reduction performance. Two stages of calibration were conducted, with the first stage to calibrate the inflow and pollutant concentrations, and the second stage to further calibrate the k-C* model to fit the experimental results. The validation of the model was done using the percentage bias between modeled and experimental data to evaluate the accuracy of bioretention modeling using MUSIC software. Overall, the accuracy of this model increased after calibration and can be accepted, as the performance of bioretention models for total suspended solids, total nitrogen, and total phosphorus removal percentage are good or very good (-13%, -4%, and -39% respectively), whereas the flow rate reduction is satisfactory (17%).