During the last decade, sustainable fashion has attracted increasing attention from policymakers, firms, and consumers. This interest is also reflected in consumer behavior research in this area. Notwithstanding this, there are few systematic literature reviews from a consumer behavior perspective. The purpose of this paper is to systematically review and critically assess the studies on consumer behavior in sustainable fashion to identify the research gap in this context and inform a future research agenda. A total of 167 journal articles were identified, and a final sample of 88 articles synthesized. A descriptive analysis was performed to examine the research methods, research trends, and theoretical underpinnings. Separately, a synthetic analysis was performed using the Stimulus-Organism-Response (S-O-R) framework. Findings reveal a significant increase in the volume of publications since 2009. Qualitative, experimental, cross-cultural, and longitudinal studies are significantly less represented in the literature. No evidence of research using big data techniques were identified. Much of the research published is not adequately grounded in theory. The findings also suggest that the consumer attitude-behavior gap requires further exploration. This review fills a need to summarize the current state of consumer behavior in sustainable fashion literature and provides valuable insights into the existing marketing corpus on the topic. Moreover, the review identifies a number of outstanding research gaps that can inform future research.