Voluntary Sustainability Standards and ecolabels are market-based mechanisms used to encourage producers and consumers toward environmental sustainability. The Marine Stewardship Council (MSC) aims to improve ocean health and promote a sustainable seafood market. There is growing interest in the program’s impacts (direct and indirect) from changes to fisheries management and consumer awareness to market access and the reputation of fisheries. To better understand what is known about the program’s impacts and the quality of evidence available, this map collates and describes articles on the environmental, social, institutional and economic effects of the MSC, identifying the methods used to determine impacts, and highlighting knowledge gaps and clusters. Following an a priori protocol, systematic searches of peer-reviewed literature were conducted in Web of Science, SCOPUS and AGRIS. Grey literature was gathered from Google Scholar, Microsoft Academic, and three subject-specific websites. A total of 771 articles were retrieved, 271 of which were screened at full-text. 28 articles met all inclusion criteria and a further 37 met all the criteria but did not have a comparator. Additionally, 108 articles that describe the MSC but do not investigate its impacts (thus failing on ‘comparator’ and ‘outcome’ inclusion criteria) were included in the narrative report. This provides an overview of MSC topics that are of general interest to researchers in comparison to articles that investigate MSC’s impact. Evidence of the impact of MSC certification fall in the following topic categories: economic (38%), environmental (25%), governance (29%) and social (8%). These articles documented diverse outcomes related to MSC certification. The most common are price premiums, market access, changes in stock health, ecosystem impacts and fisheries management changes. A key knowledge gap are articles on the effects of the MSC’s Chain of Custody Standard and its effects on the supply chain. Generally, literature focused on European and North American fisheries with little focus on fisheries situated in lower-income countries. Research interest in the MSC has grown over the last two decades, however, little research uses study designs and evidence that can robustly detect or attribute change to the MSC. Greater focus on conducting robust quasi-experimental designs would help to better understand the program effects. Comparing areas of interest in the general literature (which, for example, shows greater focus on the governance aspects of the programme than found in literature using comparators) suggests that this is partly due to lack of resources, data access and the challenge of obtaining counterfactuals. Nevertheless, some topics were absent in all areas, such as the social and economic dynamics that link harvesters and supply chain actors. It is important to fill the identified knowledge gaps as the behaviours of certified harvesters, supply chain actors and other stakeholders are the key through which the public influence sustainability, market inclusion/exclusion operates, and inequality is generated. Understanding these processes can have wider relevance in the field, informing the design of other sustainability interventions.