Aspergillus flavusis a major aflatoxin B1, posing significant health concerns to humans, crops, and producer fungi. Due to the undesirable consequences of the usage of synthetic fungicides, biological control using yeasts has gained more attention. In this study, eight isolates of epiphytic yeasts belonging toMoesziomycessp.,Meyerozymasp. andMetschnikowiasp., which have been identified as antagonists, were isolated from different plants, including grapes, blueberries, hawthorns, hoşkıran, beans and grape leaf. While volatile organic compounds (VOCs) produced byMoesziomyces bullatusDN-FY,Metschnikowiaaff.pulcherrimaDN-MP andMetschnikowiaaff.pulcherrima32-AMM reduced in vitroA. flavusmycelial growth and sporulation, only VOCs produced byMetschnikowiaaff.fructicola1-UDM were found to be effective at reducing in vitro AFB1production. All yeasts reduced the mycelial growth ofA. flavusby 76–91%, while AFB1production reduced to 1.26–10.15 ng/g and the control plates’ growth was 1773 ng/g. The most effective yeast,Metschnikowiaaff.PulcherrimaDN-HS, reducedAspergillus flavusgrowth and aflatoxin B1production on hazelnuts. The AFB1content on hazelnuts reduced to 333.01 ng/g from 536.74 ng/g. To our knowledge, this is the first report of yeasts isolated from plants being tested as potential biological control agents to reduce AFB1production on hazelnuts.