To assess sustainable attitudes towards environmental issues, understanding the most impactful variables amongst sub-dimensions of attitudes proves critical. In this research, the subdimensions of attitudes of students towards environmental challenges were modelled. An online Likert-scale questionnaire, spanning from 1 'Strongly Disagree' to 5 'Strongly Agree', was administered to 380 high school and associate degree students in Afyonkarahisar city center between 15 September and 15 November 2022. The questionnaire aimed to gauge the students' attitudes using the Affective, Cognitive, and Behavioural sub-dimensions. Results revealed a statistically significant effect coefficient of 0.557 between the cognitive and affective attitudes. In a similar vein, the cognitive attitude's impact on behavioural attitude was found to be statistically significant with an effect coefficient of 0.534. However, a coefficient of 0.017 between affective and behavioural attitudes demonstrated no statistically significant mediator effect. Contrary to the initial hypotheses surrounding the mediator effect of affective attitude on behavioural attitude, the findings indicate that cognitive and affective attitudes independently influence behavioural attitude. Within the cognitive dimension, the awareness of the escalating environmental problems emerged as a paramount item. It is implied that for fostering sustainable environmental behaviour, the cognitive dimension plays a pivotal role.