Universities today have increasingly introduced and integrated sustainability elements into their curriculum to nurture students into potential future leaders for sustainability. Although various types of pedagogies have been introduced for the development of sustainability competencies in students, not many studies have investigated engagement in campus sustainability activities as a pedagogical tool. In that respect, this paper attempts to bridge the gap by investigating the potential of engagement as a pedagogical tool and how it can help in developing sustainability competencies in students. The investigation was conducted at three local universities in Malaysia, where purposive sampling was employed for the selection of data. This sampling technique is capable of carefully selecting respondents that are relevant to this investigation given the number of students involved in campus sustainability activities is small in comparison to the total student population. In-depth interviews were conducted with 21 students who have been identified from the purposive sampling and considered as the most active and proactive volunteers in their respective campus sustainability activities. Respondents shared their experiences where ‘interpersonal competency’ was emphasised as the most developed and essential competency for them throughout their engagement. Another interesting finding is the importance of ‘passion’. Having a strong sense of enthusiasm for sustainability not only serves as a push factor that drives these students to put their efforts into achieving the objectives of the campus sustainability activities they are involved in but also acts as an important catalyst to the development of sustainability competencies as a whole.