This paper demonstrates the performance enhancement of a terahertz (THz) patch antenna through the integration of metamaterials (MTM). The proposed design is a rectangular slotted patch antenna operating at 3.62 THz, utilizing an FR4 substrate with a dielectric constant of 4.4, a loss tangent of 0.04, and a thickness of 2 μm. The incorporation of MTM leads to significant improvements in the antenna’s performance metrics. Specifically, the integration enhances the impedance matching, with a reflection coefficient improvement from −35.09 dB to −41.63 dB, indicating reduced signal reflection and better power transfer. The MTM also enhances the radiation characteristics of the antenna, increasing the gain from 3.98 dB to 6.04 dB, and boosting the directivity from 5.35 dB to 7.49 dB, resulting in more focused radiation. All these enhancements underscore the potential of MTM to optimize THz antenna performance for advanced 6G communication and biomedical applications.