Chemical, biochemical, and physicochemical properties of materials vary immensely at the nanoscale mainly due to the high aspect ratio of surface area to volume. The unique morphological characteristics (shape, size, and charge distribution) and physicochemical properties of nanomaterials lead to considerable differences in mechanical properties, melting point, optical absorption, thermal, electrical conductivity, biological, and catalytic activities. As such, the synthesis of nanoparticles of diverse sizes and shapes has underpinned great interest due to their novel properties as compared to their bulk counterparts. “Green” synthesis has gained extensive attention as eco-friendly method for synthesizing a wide range of materials/nanomaterials including metal/metal oxides nanomaterials, hybrid materials, and bioinspired materials. Green synthesis is regarded as a safe, simple, sustainable, and cost-effective alternative tool in comparison with traditional methods of synthesis commonly used in laboratory and industry. In the general literature review, the biosynthesis of metallic (Ag, Au) nanoparticles from microorganisms or macroalgae is commonly reported. In our investigation, we report for the first time the direct synthesis of inorganic ZnS nanoparticles from biological extract of brown algae collected on West Africa seashore. The synthesis mechanism is discussed according to different experimental characterizations (XDR, SEM, TEM, FTIR, HPLC). We highlight the role of secondary metabolites in the sequestration of atomic Zn prior to nucleation of ZnS nanocrystals.