This manuscript prescribes the design of a four-port ultra-wideband (UWB) diversity antenna combined with 2.4 GHz ISM radio band. The denim-based wearable antenna is intended for use as a radio frequency identification (RFID) tag for tracking and security applications. The unit cells of the antenna are arranged orthogonally to each other to achieve isolation $gt15$ dB. The bending analysis of the proposed antenna is performed to ensure its stability. The dimensions of the unit cell and four-port MIMO antenna are $30 times 17 times 1$ cubic millimeter and $55 times 53 times 1$ cubic millimeter, respectively. The proposed antenna’s specific absorption rate (SAR) is researched in order to determine the safer SAR limit set by the Federal Communications Commission (FCC).