Knowledge is a vital resource for both understanding and addressing pressing social–ecological challenges of our time. Sustainability scientists have thus increasingly turned their attention to the role and relevance of knowledge for societal change. However, as identified in this study, the research landscape is very broad and fragmented, with little convergence on definitions between scholarly communities. We comprehensively map knowledge-related concepts and their uses in sustainability science, while eliciting points of agreement and controversy across bodies of literature. Clarifying terminology is a first step towards better empirical science and theory building, and ultimately enhances our ability to leverage knowledge for action and decision–making. Our analysis also suggests five entry points to thinking about knowledge in sustainability science: (1) knowledge as system; (2) as entity, or (3) as process; (4) knowledge for and through learning; and (5) knowledge at interfaces. We discuss how, taken together, these perspectives can contribute to a better understanding of the multiple ways in which knowledge can serve sustainability.