Hyperlipidemia is a chronic metabolic disorder in humans, contributing to the onset of cardiovascular diseases (CVDs) that remain the leading cause of death worldwide. Current clinical antihyperlipidemic agents are often accompanied by diverse adverse side effects. Therefore, developing safer novel lipid regulators is an urgent and challenging task. Marine polysaccharides exhibit remarkable antihyperlipidemic activity owing to their distinctive physicochemical properties, multi-target mechanisms, and system-level modulation. This review systematically summarizes recent progress regarding the antihyperlipidemic efficacy of marine polysaccharides and provides comprehensive insights into their sources, structural features, structure–activity relationships, mechanisms of action, and application potential. Furthermore, this review also highlights the existing limitations and challenges in translational research of marine polysaccharides, and puts forward future research directions to advance marine polysaccharides into safe, effective, and sustainable natural therapeutics for hyperlipidemia.