In this study, a millimeter-wave (MMW) U-Shaped slot antenna is designed for 5G applications. The main aim of the 5G technology is to supply a very high bandwidth to the users. Because of this reason, the main aim of this study is to enlarge the operating frequency bandwidth with a very low cost compact manner. So as to achieve these design requirements, the defected ground structures (DGS) are utilized in a rectangular shape symmetrically in the design. DSG method enlarges the operating frequency bandwidth from 26.7 GHz to 40.9 GHz. Moreover, the antenna is developed with utilizing simple structures with a total 9x9 mm(2). compact size; so as to decrease the manufacturing costs. In the design, performance the return loss, current distribution and the radiation pattern are investigated to monitor the performance of the designed antenna. The antenna design is simulated in both CST and HFSS simulation softwares and it is seen that simulation results are shown a good agreement to each other.