Alginate, known for its unique properties such as biocompatibility, biodegradability, and gel forming capability, has emerged as a corrosion-resistant material in aqueous environments for sustainable and environmentally friendly solutions. Further, alginate-based composites possess self-healing features through their distinctive molecular structure, encapsulating unprotected metal surfaces and preventing additional corrosion. As a result, alginate-based coatings on metals provide extended corrosion protection while requiring less frequent maintenance, which is highly attractive for long-term use in hostile settings. In this review, we comprehensively explore the diverse applications of alginate-based coatings, with a focus on their roles in corrosion inhibition, antifouling, and biocidal activities. After a brief introduction to the fundamental principles of corrosion-resistance behaviors, we will examine the interfacial and surface properties that make alginate-based coatings effective for these protective functions. This includes an analysis of their molecular structure, amphiphilic nature, and specific attributes that contribute to their effectiveness in various industrial applications such as ship hulls, undersea structures, and maritime equipment. We also review the current state of research, evaluation methods, and comparative analyses with traditional coatings in each segment. Last, the review highlights the advantages of alginate-based coatings, along with the challenges and future perspectives.