To demonstrate the potential of the fifth edition of the Headway EFL textbook as a means to cultivate sustainability awareness and competence in Education for Sustainable Development (ESD), this study aims to identify themes related to the Sustainable Development Goals (SDGs) within the textbook. The secondary objective is to identify grammatical concept exercises that can function as a means of augmenting sustainability competencies. Drawing on constructivism research philosophy, this study utilized a content analysis approach to identify themes and patterns of SDGs in the textbook. This involved connecting language skill development (reading, listening, writing, and speaking) within every topic unit of the textbook with each of the 17 Sustainable Development Goals (SDGs). Furthermore, we focused on identifying and correlating different grammatical tasks that have the potential of enhancing students’ anticipatory, system-thinking, normative, strategic, and interpersonal sustainability competencies. The findings indicated that, with the exception of SDGs 6 and 1, all of the remaining 15 Sustainable Development Goals (SDGs) are depicted throughout the six levels of the textbook. In addition, it was revealed that exercises pertaining to grammatical concepts, including passive voice, pronouns, conjunctions, adjectives, and emphatic language, simple future tense, serve as significant predictors and enhancers of the five core competencies of sustainability. The present study sheds more light on the current understanding of sustainability awareness and competencies that are crucial for advancing Education for Sustainable Development (ESD) initiatives across various levels of the educational system.