The aim of this study is to explore the possibility of using recycled Juncus Acutus-fibers waste as an additive to unfired clay bricks for construction purposes. This novel approach aims to provide an alternative to disposing of Juncus Acutus plants in landfills and waterways by recycling the waste and incorporating it into the construction industry. The study evaluates the physical and mechanical characteristics of prepared brick samples with varying proportions of recycled Juncus Acutus-fiber waste additives (from 0%, 1%, 3%, 5%, 7% and 10% by weight), in accordance with Moroccan building sector testing standards. A uniform mixture was produced using a consistent mixing technique with an electric stirrer. The clay utilized was classified as Illite and exhibited non-swelling characteristics with a significant SiO2 content. The produced brick samples were discovered to be lightweight, with bulk densities beneath 1.75 g/cm3. By adding a significant amount of additive, it was possible to significantly reduce the shrinkage rate of the produced samples. In fact, while the reference sample had a shrinkage rate of 8%, adding 10% of Juncus fibers resulted in a sample with a shrinkage rate of only 0.7%, a reduction of 90%. However, the compressive strength decreased significantly as the amount of Juncus fibers increased. Nevertheless, the produced samples are suitable for use in the construction industry in accordance with the German standard DIN 18945(2013–08).