Over the last two decades, efforts to combat illegal, unreported, and unregulated (IUU) fishing have led to an expansion of initiatives to enhance transparency across the seafood industry through international agreements, national government regulations, and voluntary private initiatives. Understanding of the effects of these initiatives remains limited, and approaches contested among stakeholders. Yet similar transparency initiatives introduced in recent decades across other sectors whose goal is to expand sustainability in global supply chains, may offer applicable lessons for seafood sustainability. Through a comparative review of transparency initiatives adopted in apparel, extractives, and timber supply chains, this study draws out lessons to inform efforts to expand transparency in seafood supply chains in order to combat illegal fishing. Across the literature reviewed on these three industries and seafood, there was mixed consensus that the initiatives met their intended sustainability goals or significantly affected costs and revenues, based on the evidence available. The review finds a trend across the three industries for increased transparency initiatives in international supply chains, which are often voluntary or state-based initiatives. This trend was commonly motivated by expanded trade and reputational risks from consumer demand, and external pressure from civil society. Transparency initiatives were often driven by governments, lead firms, and markets from developed countries. Conversely the resources and/or producers targeted by the transparency activities have been more widely dispersed worldwide, with many located in developing countries. Comparing across the sectors, lessons learned are distilled to inform efforts aiming to expand transparency in seafood supply chains.