Eco-labels are essential for informing consumers about products’ environmental characteristics. However, the many different labels consumers encounter can be confusing, which makes assessing environmental quality associated with each label difficult. How does consumer misperception of competing eco-labels affect market structure and welfare? This article provides theoretical insight into this issue by using a double-differentiation model in which three products compete: an unlabeled product and two distinctly eco-labeled products, one with a medium and one with a high level of environmental quality. The study investigates the effects of consumers’ imperfect information when they perceive all eco-labels as a sign of the same high environmental quality and consider each label as a unique product. This misperception can weaken the firm that provides the greenest product, though paradoxically this situation is not always detrimental to social welfare. However, depending on the certifying organizations, consumer misperception can induce firms to use a greenwashing strategy and encourage nongovernmental organizations and regulators to introduce less stringent standards.