Sustainability for Universitas Islam Indonesia (UII) is not only about ranking, but also about usefulness. Because the ranking is only an impact. Not a destination. This is proven by several non-credible rankings whose data collection is sometimes colored by manipulation. Universitas Indonesia (UI) GreenMetric World University Rankings is of course not included in it. Because this ranking is the only institution that doesn’t just collect data and show off the ranking at the end. However, there are also efforts to maintain sustainability. Therefore, UII is committed to ensuring that sustainability development experiences and initiatives are part of realizing the university’s vision. Universitas Islam Indonesia aspires to become a mercy for all humankind (rahmatan lil ‘alamin), an internationally recognized university committed to perfection and Islamic values in the field of education, research, community service, and da’wa. Mercy for all is the essence of the university’s vision. Mercy is not only about religious life, but also human survival including the ecosystems that adjoin it, namely sustainable environment. This article talks about UII’s experience in overseeing sustainable environmental initiatives, all of which were inspired by participation in the UI GreenMetric World University Rankings Networks (UIGWURN). The main point from this paper is about implementation of rahmatan lil ‘alamin towards sustainability, especially in lesson learned. These various sustainability developments are not only individualistic ideas. However, it also comes from lessons learned when participating in various UIGWURN activities.