Abstract: Natural extracts and compounds from marine resources have gained intensive scientific and industry attention for radioprotective activities in the past ten years. However, the marine-derived radioprotectants have been studied against UV-rays, gamma (γ)-rays and X-rays for more than 30 years. This review aims to identify key marine-derived extracts/compounds and their modes of action studied for radioprotective activities from 1986 to 2019. A comprehensive survey was conducted to establish the trend in terms of the publications each year and the countries of origin. A total of 40 extracts and 34 natural compounds showing radioprotective activities against UV-rays, gamma (γ)-rays and X-rays were identified from a range of marine plants and animals. These extracts and compounds are broadly categorized into polysaccharides, phlorotannins, carotenoids and mycosporine-like amino acids (MAAs). Macroalgae and microalgae were found to be the dominant sources of polysaccharides, phlorotannins and carotenoids. MAAs were mainly identified in algae, sponges, sea cucumber and corals that showed significant UV-absorbing activities. A number of radioprotective mechanisms were shown by these compounds, predominantly free radicals scavenging, inhibition of apoptosis, UV-ray absorption and DNA damage-repair signaling pathways. While these bio-discoveries warrant further investigation and development of radioprotective therapeutics, however, the lack of clinical studies is a major obstacle to be tackled in the future.