One-third of people will be diagnosed with cancer at some point in their lives, making it the second leading cause of death globally each year after cardiovascular disease. The complex anticancer molecular mechanisms have been understood clearly with the advent of improved genomic, proteomic, and bioinformatics. Our understanding of the complex interplay between numerous genes and regulatory genetic components within cells explaining how this might lead to malignant phenotypes has greatly expanded. It was discovered that epigenetic resistance and a lack of multitargeting drugs were highlighted as major barriers to cancer treatment, spurring the search for innovative anticancer treatments. It was discovered that epigenetic resistance and a lack of multitargeting drugs were highlighted as major barriers to cancer treatment, spurring the search for innovative anticancer treatments. Many popular anticancer drugs, including irinotecan, vincristine, etoposide, and paclitaxel, have botanical origins. Actinomycin D and mitomycin C come from bacteria, while bleomycin and curacin come from marine creatures. However, there is a lack of research evaluating the potential of algae-based anticancer treatments, especially in terms of their molecular mechanisms. Despite increasing interest in the former, and the promise of the compounds to treat tumours that have been resistant to existing treatment, pharmaceutical development of these compounds has lagged. Thus, the current review focuses on the key algal sources that have been exploited as anticancer therapeutic leads, including their biological origins, phytochemistry, and the challenges involved in converting such leads into effective anticancer drugs.