This study analyzes sustainability concepts through the lens of Roman Catholic Social Teaching (CST) with a special emphasis on Laudato Si’. CST expands the focus of sustainability to include social justice through its emphasis on human dignity, the common good, and caritas. In CST, justice is understood as structural while environmental obligations are connected to integral human development and peace. In Laudato Si’, Pope Francis calls on us to counter prevailing unjust systems with a structural reordering of multiple ecologies: environmental, economic, social, cultural, and daily life. Based on this reordering, he developed the notion of integral ecology, and we show how it encompasses a set of existing sustainability ideas in CST and, more importantly, how it changes the focus and scope of sustainability. Unfortunately, and despite supposed good intentions, some institutions misrepresent and use the term “sustainability” to justify systems that result in “un sustainable” consequences. We thus show how Laudato Si’ offers an antidote to such unsustainable practices by reconceptualizing the sustainability construct through the notion of integral ecology.