<p>There are recurrent calls for stronger partnerships between science and society to address numerous global environmental challenges. Underpinning many responses to such calls is an increased focus on the science-policy-practice interface (SPPI) concept. However, this concept remains unclear, with divergent interpretations, and confusion between it and similar concepts (e.g. science-policy or science-practice interface). This paper aims to address these limitations through a systematic review of SPPI studies, to create clarity and consistency for the concept, and to build a new conceptual framework for the SPPI. In the new framework, the SPPI is not only about the multi-dimensional interactions between science, policy and practice actors, but also between the processes of knowledge generation, policymaking and implementation. It extends beyond the actors’ interactions and the linear flow ‘from knowledge to policymaking to implementation’, highlighting the multi-directional interactions of the processes, including the monitoring and feedback loop ‘from implementation to knowledge and policymaking’. The review finds that this is often overlooked in SPPI literature, yet it is necessary to advance the quality and relevance of science and policy outputs to their practical applications. The paper then outlines barriers and facilitators found in the literature that affect an effective interface in real-world contexts. Additionally, research and knowledge gaps were identified, which can guide future research directions in SPPI. Through a greater understanding of the SPPI and insights from the new conceptual framework, the paper provides practical guidance to facilitate transdisciplinary collaborations in addressing environmental challenges.</p>