This research presents the design and analysis of a compact MIMO antenna tailored for 5G millimeter-wave applications, specifically targeting bands N257, N260, and N262. The antenna, characterized by its straightforward design, maintains compact dimensions of 10 mm × 16 mm while delivering exceptional performance with high gain. Employing Rogers RT/Duroid 5880 substrate material with a thickness of 0.508 mm, the antenna consists of two crescent-shaped radiating elements (patches) situated on the top surface of the dielectric material, complemented by a slotted ground on the bottom. The radiating elements are fed through a 50-Ω microstrip line. Operating across three distinct bands, the antenna’s capabilities are outlined as follows: the first band spans from 27.2 to 29 GHz, centering around 28 GHz; the second band encompasses the frequency range from 34 to 40.2 GHz, with a center frequency of 39 GHz achieved through slotting crescent-shaped radiating elements; the third band, ranging from 47.5 to 51.3 GHz with a center frequency of 48.7 GHz, is attained by engraving circular slots on the ground. To validate simulation outcomes, a hardware prototype of the antenna is manufactured, showcasing excellent agreement between simulations and measurements. The antenna design is implemented using the CST Microwave Studio software tool and is benchmarked against existing literature. Key attributes of the proposed antenna include its compact size, simple geometry, wide bandwidth, and high gain. The antenna’s favorable MIMO parameters (ECC, TARC, DG, and CCL), coupled with minimal spacing between elements, position it as a promising candidate for forthcoming 5G millimeter-wave communication applications.