Context: Chemotherapeutic agents and radiation therapy have been acknowledged as the sole cancer treatment, even though they cause significant adverse reactions. Recent research has demonstrated that treatment-based nanoparticles can specifically target cancer cells, thereby overcoming these detrimental effects. Nanotechnology is a promising new anti-cancer treatment since it focuses primarily on the cytotoxic processes that induce apoptosis in cancerous cells. Algae, which can be subdivided into microalgae and macroalgae, appear to be the most suitable substrate for nanoparticle synthesis among the various plant divisions utilized thus, for the bioreduction of metal nanoparticles. Objectives: This review focuses on the essential elements and techniques involved in the algal-mediated synthesis of AgNPs, as well as the cytotoxicity of these biosynthesized silver nanoparticles generated by microalgae and macroalgae against various forms of human cancer. Data Sources: Data were acquired utilizing a variety of online databases, including ScienceDirect, PubMed Central, Springer Link, National Center for Biotechnology Information, and ResearchGate. The accumulating literature highlights the unique properties of AgNPs produced by various algae, their method of anti-proliferative action, and their cytotoxic evaluation of several cancer cell lines. Results: This review found that the antiproliferative effect of macroalga and microalga biosynthesized silver nanoparticles is dependent on particle size, concentration, and cancer cell lines tested. Since their high growth rate and short harvesting technique without causing damage to normal cells, macroalgae are more typically used to synthesize AgNPs than microalgae in this research.