Seaweed is an enormous resource comprised with natural bioactive compounds comprise with several therapeutic effects including anticancer activity. In this context, the biochemical composition of seaweeds plays a major role. Many biochemical compounds extracted from seaweeds and crude extracts, such as aqueous, methanolic account mainly for the anticancer effect against several cancer cell line. In this contrast seaweed extracts inhibit cancer cell growth and proliferation by inducing apoptosis and inhibit metastasis activity. In this review, biochemical and anticancer properties of seaweeds are discussed and this will provide the basic information to develop a novel chemotherapeutic drug to challenge the cancer.