The aim of the present study is to improve the quality of students' environmental literacy and sustainability education in chemistry teaching by combining the socio-scientific issue of life-cycle thinking with inquiry-based learning approaches. This case study presents results from an inquiry-based life-cycle thinking project: an interdisciplinary teaching model designed by chemistry teachers. The strength of the project is that upper-secondary students (N = 105) are allowed to investigate the life cycle of an optional product based on their own interest. Student-centred teaching methods are suggested to promote the students' interest in studying. The research question was: How does an inquiry-based life-cycle thinking project in chemistry education affect students' chemistry attitudes and environmental literacy? The research methods used included surveys and semi-structured interviews. The study shows that the project positively affected students' attitudes towards chemistry learning: they valued the independent and collaborative learning setting. The changes in the students' environmental literacy were evident in their new realisations: they emphasised the importance of environmental protection and recycling, but perceived that changing their own behaviour is still difficult. The inquiry-based teaching of life-cycle thinking can be seen as an effective approach to more motivating and sustainable chemistry education. Further research should address the kinds of knowledge outcomes that this type of inquiry-based life-cycle teaching creates in students. Furthermore, other useful approaches to teaching sustainable development in chemistry lessons should be shared.