<p>Biobased nanoparticle (NP) synthesis has recently gained widespread attention as an eco-friendly, simple, safe, sustainable, and relatively cost-effective substitute compared to the traditional routes of NP making. Metal NPs have a broad scope in nanomedicine because of their intriguing catalytic, chemical, optical, and electronic properties and play an essential role in the healthcare industry. The process of microalgae-based NP synthesis is considered preferred and shows advantageous properties such as the lack of toxic yields, less energy consumption, high scalability, and a few more. The secondary metabolites derived from microalgal species reduce cap and stabilize metal precursors to NPs (metal, metal oxide, or bimetallic). The synthesis could occur intra- or extra-cellularly based on the NP formation site and reducing agents. The NP biosynthesis using microalgae has been reviewed for numerous biomedical applications, namely, antibacterial, antifungal, antiviral, antioxidant, anti-cancerous, and other biomedical applications because of its unique physicochemical properties, biocompatibility, and non-toxic nature. This review highlights the basis behind the biosynthesis of NPs and its procuring methods from various microalgae. Furthermore, special attention to the critical understanding of the biosynthesis mechanism of NPs from microalgae, various process parameters affecting its production, and their biomedical applications has been reviewed critically.</p> Graphical Abstract <p></p>