The promise of innovation in humanitarian contexts has generated an expanding literature, from academics as well as practitioners. However, the field has become characterised by conceptual ambiguity and insular approaches, inhibiting the integration of findings and best practices. Therefore, this paper aims to identify the key concepts, definitions, and themes in humanitarian innovation (HI) research by applying a systematic literature review and content analysis. Based on data from 301 publications, we analyse scholarly and practitioner articles addressing the topic of humanitarian innovation. Our analysis suggests that efforts to reform the humanitarian system by leveraging innovation have been primarily ad hoc, fragmented, and serving miscellaneous separate objectives. This results in the implementation of incremental improvements, rather than transformative change throughout the sector. To bridge the gap between the various conceptualisations of HI, we propose a conceptual framework that provides a system perspective on HI, which includes the institutions, actors, contextual factors, and outputs of the system. The implications of our finding for further research and policy are discussed as well.