Corporate social responsibility (CSR) in the seafood industry is on the rise. Because of increasing public awareness and non-governmental organization (NGO) campaigns, seafood buyers have made various commitments to improve the sustainability of their wild seafood sourcing. As part of this effort, seafood suppliers have developed their own CSR programs in order to meet buyers’ sourcing requirements. However, the CSR of these companies, many of which are mid-supply chain or vertically integrated, remain largely invisible and unstudied. In order to better understand how mid-chain seafood suppliers engage in sustainability efforts, we reviewed the CSR practices of the 25 largest seafood companies globally (by revenue) that deal with wild seafood products. Based on literature, existing frameworks, and initial data analysis, we developed a structured framework to identify and categorize practices based on the issues addressed and the approach used. We found companies implement CSR to address four key areas, and through various activities that fit into five categories: Power; Practices; Partnerships; Public policy; and Philanthropy. One of the biggest gaps identified in this study is the lack of accountability mechanisms, as well as robust and consistent accounting of impacts. Indeed, many companies express commitments without clear goals and structures in place to ensure implementation. Therefore, improvements in seafood company performance on social and environmental aspects may not only require creating a better business case for CSR, but also require ensuring that companies have the necessary processes and structures in place through public oversights and regulations.