This study presents a novel, compact, diamond-shaped Multiple Input Multiple Output (MIMO) antenna system for 5G wireless communication. The proposed MIMO antenna system encompasses an array configuration, with each array unit comprising two antenna elements. The array elements are then orthogonally oriented making it a dual-port MIMO antenna system. The system is printed on a commercially available Rogers 5880, characterized by a permittivity ( epsilon(r) ) of 2.2 and a loss tangent (tan( delta) ) of 0.0009. The overall dimensions of the MIMO antenna system are 26 x 16 x 0.254 mm(3), operating in an mm-wave band with a frequency spectrum spanning from 26.2 to 34.2 GHz. The single antenna element exhibited a gain of 3.8 dBi and is then improved up to 7.6 dBi with two elements array arrangement. The system exhibited satisfactory MIMO characteristics with a maximum diversity gain of 10 dB, an envelope correlation coefficient of less than 0.0005, and an impressive 25 dB isolation between the antenna elements. Moreover, the proposed MIMO antenna array consistently maintained a radiation efficiency exceeding 90% across the entire desired frequency spectrum. Measurements were conducted with fabricated prototypes to validate the simulation results and were found in good agreement. The remarkable features of the proposed MIMO antenna system, such as compact size, wide bandwidth, good efficiency, and satisfactory gain values make it a promising candidate for 5G millimeter-wave wireless communication networks.