Objective <p>This study aimed to assess levels of awareness, knowledge, attitudes and behaviors related to climate change and sustainability in health care among final-year medical students (intern doctors), and to examine the relationships between these domains.</p> Methods <p>This descriptive, cross-sectional study was conducted between 12 August and 24 October 2025 among intern doctors enrolled at Gaziantep University Faculty of Medicine. Data from 167 interns who agreed to participate and completed the questionnaire in full were analyzed. Data were collected via an online questionnaire developed by the researchers based on a literature review, consisting of sections on sociodemographic characteristics, awareness, objective knowledge, attitudes and behaviors related to climate change and sustainability in health care. Total scores were calculated for the awareness, knowledge, attitude and behavior sections. Descriptive statistics, t tests, one-way analysis of variance, Pearson correlation and hierarchical multiple linear regression were used for data analysis. Internal consistency of the questionnaire sections was assessed using Cronbach’s alpha coefficients.</p> Results <p>The mean age of participants was 24.03 ± 1.36 years, and 52.1% were female. While perceived knowledge was mostly rated as low or moderate, objective knowledge scores indicated that 44.9% of students had moderate and 53.3% had good knowledge levels. Mean awareness scores were high (6.04 ± 1.27), attitude scores reflected moderately positive attitudes (6.38 ± 1.18), and behavior scores were lower, particularly in daily-life and clinical practice domains (overall behavior score 10.31 ± 3.89). Only 7.8% of participants reported discussing climate change with most of their patients; the most frequently reported barriers were lack of time (75.4%), perceived patient disinterest (69.5%) and insufficient knowledge (60.5%). Cronbach’s alpha coefficients for the awareness, attitude and behavior sections were 0.65, 0.70 and 0.78 respectively, indicating acceptable internal consistency, whereas the coefficient for the knowledge section was 0.40. Higher perceived knowledge and greater involvement in sustainability initiatives within the hospital were associated with significantly higher scores in some behavior domains. There was a weak but statistically significant positive correlation between knowledge and attitude scores (<i>r</i> = 0.172, <i>p</i> = 0.026), whereas no significant relationships were observed between knowledge or awareness scores and behavior scores.</p> Conclusion <p>Although intern doctors demonstrated relatively high levels of awareness and knowledge regarding climate change and sustainability in health care, these did not fully translate into corresponding changes in clinical and everyday behaviors. The weak relationship between knowledge and behavior suggests that information alone is insufficient to drive behavior change, and that motivational, institutional and structural support mechanisms are needed. Medical education should therefore be restructured to strengthen the climate-health nexus through both theoretical content and the promotion of environmentally sustainable clinical practices.</p> Trial registration <p>Not applicable. This study did not involve a health care intervention or clinical trial.</p>