This paper synthesizes empirical evidence on the environmental and socioeconomic impacts of petroleum exploration and production in the Niger Delta, Southern Nigeria, focusing on soils, surface and groundwater, and local livelihoods. A review of field-based studies, environmental assessments and community surveys reveals pervasive hydrocarbon contamination (TPH, PAHs), elevated heavy-metal concentrations, and widespread degradation of mangrove and farmland soils. Contaminants migrate into surface waters and shallow aquifers, impairing drinking-water quality and fisheries. Empirical studies also document reduced agricultural yields, loss of fish catches, health complaints, and livelihood erosion—effects compounded by weak monitoring, delayed spill response and chronic seepage from aging pipelines. Remediation efforts (engineered excavation, bioremediation, phytoremediation) show variable success; cost, ecological sensitivity (mangroves) and governance deficits limit large-scale recovery. The synthesis concludes that meaningful restoration requires coordinated long-term remediation, rigorous monitoring, community engagement and strengthened regulatory enforcement. Priority actions include hotspot remediation, alternative livelihood support, and establishing transparent contaminant and health-monitoring systems.