In this article, by drawing on empirical evidence from twelve case studies from nine countries from across the Global South and North, we ask how radical grassroots social innovations that are part of social movements and struggles can offer pathways for tackling socio-spatial and socio-environmental inequality and for reinventing the commons. We define radical grassroots social innovations as a set of practices initiated by formal or informal community-led initiatives or/and social movements which aim to generate novel, democratic, socially, spatially and environmentally just solutions to address social needs that are otherwise ignored or marginalised. To address our research questions, we draw on the work of Cindi Katz to explore how grassroots innovations relate to practices of resilience, reworking and resistance. We identify possibilities and limitations as well as patterns of spatial practices and pathways of re-scaling and radical praxis, uncovering broadly-shared resemblances across different places. Through this analysis we aim to make a twofold contribution to political ecology and human geography scholarship on grassroots radical activism, social innovation and the spatialities of resistance. First, to reveal the connections between social-environmental struggles, emerging grassroots innovations and broader structural factors that cause, enable or limit them. Second, to explore how grassroots radical innovations stemming from place-based community struggles can relate to resistance practices that would not only successfully oppose inequality and the withering of the commons in the short-term, but would also open long-term pathways to alternative modes of social organization, and a new commons, based on social needs and social rights that are currently unaddressed.