Marine-derived polysaccharides such as alginate, carrageenan, chitin, fucoidan, ulvan, and floridean starch play a significant role in the global food industry due to their diverse functional attributes, including gelling, thickening, stabilizing, and potential health benefits. This chapter provides a comprehensive overview of the regulatory frameworks governing the use of these polysaccharides in major international regions, including the United States, the European Union, Japan, China, South Korea, Australia/New Zealand, India, and Canada. It highlights important regulatory classifications such as “Generally Recognized as Safe” (GRAS) designations, assessments of acceptable daily intake (ADI), and recent updates from authorities like the FDA, EFSA, MHLW, FSANZ, and Codex Alimentarius. The chapter also examines safety profiles based on toxicological data, historical dietary usage, and contemporary risk assessments, with a particular emphasis on vulnerable groups, such as infants. Additionally, emerging polysaccharides, such as fucoidan and ulvan, are discussed in light of increasing regulatory attention and their growing significance in the functional food market. By integrating current scientific evidence with regulatory perspectives, this chapter provides insights for researchers, food developers, and regulatory professionals involved in the application and oversight of marine-based polysaccharides in food systems.