Focusing on Marine Harvest ASA, the world’s largest salmon producer, this article examines the role of corporations in promoting sustainable aquaculture and regulation, exploring why a leading multinational may choose to adopt and implement a proactive sustainability strategy. It develops a neo-pluralist model for conceptualizing drivers behind proactive strategy formation, and finds that a company-specific combination of simple and mixed motives linking profit-maximization and risk calculations to a longer-term normative sustainability agenda can explain why corporations become entrepreneurs for sustainability. It concludes with some reflections on implications of the findings for understanding business in environmental governance more broadly.