This study investigated the mediating role of Disposition toward Critical Thinking in the relationship between school climate and media literacy among female high school students. The research employed a descriptive–correlational design. The statistical population included all female students in the second level of public high schools in District 4 of Tehran during the 2024–2025 academic year. Using Cochran’s formula, a sample of 360 students was selected through multistage cluster random sampling. Data were collected using the School Climate Questionnaire (Lee et al., 2017), Ricketts’ Critical Thinking Disposition Inventory (Ricketts, 2003), and the Falsafi Media Literacy Questionnaire (Falsafi, 2014). Data were analyzed using structural equation modeling (SEM) in AMOS. The results revealed that school climate positively predicted both disposition toward critical thinking and media literacy. Furthermore, critical thinking disposition significantly mediated the relationship between school climate and media literacy (β = 0.27, p < 0.001). The coefficient of determination (R²) for media literacy was 0.26, indicating that the two predictors explained 26% of its variance. Overall, the findings highlight that a supportive and positive school climate promotes critical thinking, which in turn enhances students’ media literacy—emphasizing the importance of fostering educational environments that build critical and informed learners.