In this study, we aimed to determine the extent to which secondary school students practise environmental ethics. To this end, we used a questionnaire-based survey to accomplish the purpose of the study. The study's variables included knowledge, value, care, and responsibility in environmental ethics. We selected a sample of 180 students using systematic random sampling from a population of 347 Form Four secondary school students studying geography in Papar, Sabah, Malaysia. The findings showed that all study variables, knowledge, value, care and responsibility were at high levels. Furthermore, a multiple regression analysis revealed that the value and care variable in environmental ethics influenced the responsibility variable which contributed 14.5% and 2.7%, respectively to student's environmental ethics. Based on the findings, we concluded that students who incorporate environmental ethics into their daily lives will successfully fulfil their environmental ethics responsibilities. The study's implications suggest that environmental education in schools exposes students to environmental ethics and helps them develop more ethical and disciplined attitudes towards the environment.