Background <p>In light of increasing environmental problems, food safety risks and healthy living requirements, sustainable nutrition has become a priority for individuals and societies. In this context, the present study aims to develop a web-based educational program to promote sustainable dietary habits for young adults and to evaluate the effectiveness of this program. </p> Methods <p>A total of 397 young adults in Türkiye participated in a web-based sustainable nutrition education comprising eight modules: quality labels, seasonal food and avoiding food waste, animal welfare, meat reduction, healthy and balanced diet, local food, low fat, and summary module. Each education module is approximately 3–4&#xa0;min long, and the total education time is 30&#xa0;min. A pre-post design was used to evaluate participants before and 4&#xa0;weeks after the education. Data were collected at pre-education on demographic characteristics, anthropometric measurements, e-Healthy Diet Literacy scale, sustainable food preferences, and Sustainable and Healthy Eating Behaviours scale. Participants were reassessed using the sustainable food preference questions and Sustainable and Healthy Eating Behaviours scale at post-education.</p> Results <p>Web-based education significantly increased Sustainable and Healthy Eating Behaviours scores of participants from 3.9 ± 1.10 to 4.2 ± 1.24 (p &lt; 0.05). Multiple regression analysis revealed that older age, women gender, rural living, and higher pre-education scores on Sustainable and Healthy Eating Behaviours were significant predictors of higher post-education scores (<i>p</i> &lt; 0.05).</p> Conclusions <p>Web-based educational interventions have the potential to serve as an accessible and effective tool for promoting sustainable nutrition among young adults.</p>