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. Copyright © 2016 John Wiley & Sons, Ltd and ERP Environment