This chapter critically revisits Alfred Crosby’s concept of ecological imperialism, examining its enduring legacies within the twenty-first-century dynamics of land grabs, resource frontiers, and global ecological change. It traces the historical continuities from colonial conquests to contemporary corporate enclosures, highlighting how industrial agriculture, mining, and energy expansion perpetuate extractivist paradigms that undermine ecological resilience and local sovereignty. Drawing on political ecology, environmental history, and development studies, the analysis situates modern land and resource grabs within the overlapping crises of globalization, climate change, and neoliberal capitalism. Case studies from Ethiopia, Brazil, and Cambodia reveal how transnational investments restructure rural ecologies, displace communities, and entrench socio-economic dependencies under the rhetoric of development and modernization. This chapter also foregrounds grassroots resistance, indigenous ecological knowledge, and transnational advocacy networks as counterforces advancing environmental justice, food sovereignty, and alternative models of development rooted in agroecology and regenerative sustainability. Furthermore, it interrogates the geopolitical dimensions of resource competition—particularly regarding energy transitions, critical minerals, and food security—within the context of the Anthropocene’s planetary boundaries and ecological tipping points. Ultimately, this chapter argues for decolonial and post-imperial ecological frameworks that integrate justice, equity, and resilience into global resource governance, challenging extractivist trajectories while envisioning sustainable and democratic futures for both people and ecosystems.