In the face of accelerating forest degradation and deforestation, forest certification emerged in the early 1990s as a voluntary and market-based mechanism to promote environmentally appropriate, socially beneficial, and economically viable management of the world’s forests. A key goal of forest certification is to reduce forest degradation and deforestation while enhancing forest enterprises’ economic viability. However, whether forest certification contributes to meeting such goals is unclear. We conducted a systematic literature review on such impacts, reviewing empirical studies published between 1993 and 2021 regarding the impact of forest certification on forest degradation, deforestation, and economic viability. Drawing on 98 empirical studies, we analyzed these impacts and provide an overview of the studies’ findings in terms of geographical distribution, indicators considered, and the certification schemes assessed. We found that the impact of forest certification on deforestation has been specifically understudied (n = 11) compared to forest degradation (n = 42) and economic viability (n = 45). On deforestation, studies have focused on Africa (45%) and South America (36%); on forest degradation, studies have focused on Europe (40%) and Asia (20%); on economic viability, studies have focused on Asia (33%), Europe (33%) and South America (20%). We found positive-neutral (54%; 46%) impacts on deforestation, positive-neutral-mixed (70%; 21%; 9%) impacts on forest degradation and positive-negative-mixed (50%; 33%; 17%) impacts on economic viability. We did not find clear evidence that impact is linked to a specific region or certification scheme. However, scarce evidence on the impacts of the Programme for the Endorsement of Forest Certification (PEFC), the application of various methods, and site-specific indicators in the individual studies challenge such comparison and hamper the generalization of findings. This systematic review provides an overview of the state-of-the-art research on the effectiveness and economic viability of forest certification, evaluates and discusses the current evidence base, and concludes with future research lines.