Fish-skin collagen is becoming a biomaterial that is not only safe, sustainable, and of clinical value but also relevant for various applications in wound management and regenerative medicine. Free from zoonotic risks and culturally acceptable, marine collagen has striking similarities to human Type I collagen and thus exhibits excellent biocompatibility and tissue integration. Evidence from in vitro, in vivo, and clinical studies indicates that the properties of marine collagen accelerate wound healing through improved re-epithelialization, promotion of fibroblast and keratinocyte activity, and enhanced extracellular matrix formation. Acellular fish-skin grafts have significantly reduced the healing time in donor sites and diabetic ulcers, assisted by the naturally retained omega-3 fatty acids providing antimicrobial and anti-inflammatory effects. Beyond skin wound management, marine collagen improves skin elasticity, actively supports bone regeneration, and contributes to anti-aging benefits. As up to 75% of fish biomass is usually discarded, its use in biomaterial production fully aligns with the principles of a circular bioeconomy through the conversion of by-products into high-value biomaterials. Altogether, these attributes make marine collagen a promising, sustainable alternative for biomedical and cosmetic advanced applications.