Purpose: The purpose of this study is to examine the formation of sustainable development competencies (SDCs) in future primary school teachers during English for specific purposes classes, and to assess the correlation between English proficiency and the development of SDCs, including Collaboration, Strategic thinking, Critical thinking, Modelling sustainable behaviour, Systems thinking and Future thinking. Design/methodology/approach: The research experiment involved the application of content and language integrated learning and facilitation methods in three higher education institutions in Ukraine. The students' level of English language proficiency was assessed based on the results of the online Cambridge English Language Assessment test, while the level of SDC formation was measured using research methods adapted to the Ukrainian context. Findings: The experiment revealed positive changes in the levels of SDCs and English language proficiency through integrated learning and the application of facilitation methods. Originality/value: The study established a correlation between the level of English language proficiency and the formation of competencies, such as Collaboration, Strategic thinking, Critical thinking, Modelling sustainable behaviour, Systems thinking and Future thinking, all of which are vital for sustainable development.