In the environmental politics literature, cities are commonly framed as key sites for a shift towards greater sustainability and urban grassroots initiatives, such as food co-ops, urban gardening initiatives, repair cafés, and libraries of things, are commonly portrayed as such a shift’s key drivers. This paper develops a critical perspective on both common portrayals. It does so by drawing on critical urban theory, especially Lefebvre’s Right to the City. First, inspired by Lefebvre’s critique of city-centrism, the paper argues that the scope and limits of urban environmentalism hinge not only on the goals pursued but also on how the urban is framed. Urban environmentalism may mean mere lifeworld environmentalism: the greening of cities as if there were (relatively) bounded sites. Yet urban environmentalism may also mean planetary environmentalism: the mapping, problematization, and transformation of unsustainable urbanization processes that underpin given sites and lifeworlds, but also operate at beyond the latter—at a societal and planetary scale. Second, inspired by Lefebvre’s reformulation of right claims as a transformative political tool, this paper takes issue with environmental practices and discourses that present society’s niches, cracks, and margins as a key fermenting ground for radical environmental change. Since not only institutional but also bottom-up pursuits of more sustainable nature-society relations often remain stuck in mere lifeworld reform, this paper foregrounds heterodox right claims as an underexplored modus operandi in active pursuits of and discourses on radical environmental change. Heterodox right claims mean the active appropriation of dominant political languages, such as the language of right, while seeking to change the latter’s grammar. What this may mean in the realm of environmental politics, will be spelled out at hand of the example of claims to a right to public transport.