Aim: This study aimed to evaluate the relationship between environmental literacy, sustainable food literacy, and adherence to the Mediterranean diet (MD) in adults. Method: Data were collected via a web-based questionnaire created using Google Forms between April and August 2024 in Erzurum, Turkey. A total of 394 adults participated through snowball sampling. The questionnaire included sections on demographic information, anthropometric measurements, the Environmental Literacy Scale for Adults (ELSA), the Sustainable Food Literacy Scale (SFLS), and the Mediterranean Diet Adherence Screener (MEDAS). Results: 38.6% of the participants were found to adhere to the Mediterranean Diet (MD). Married participants were more likely to have adhered to the MD than single ones (odds ratio [OR]:0.41, p = 0.006). Adherence to the MD was associated with higher education duration (OR = 1.05, p = 0.011), a higher SFLS total score (OR = 1.01, p = 0.025), and a higher ELSA score (OR = 1.04, p = 0.004). Conclusion: The MD is a sustainable dietary model that enhances health and is environmentally friendly. For this reason, it may be possible to direct society towards healthier and less environmentally damaging food choices through training to increase individuals’ sustainable literacy and environmental literacy levels.