The Cambrian Explosion is commonly linked to progressive ocean oxygenation, yet recent studies indicate that early Cambrian seas remained redox-stratified and highly dynamic. How these redox fluctuations interacted with nutrient availability and biological productivity remains uncertain. Here, we reconstruct ocean redox and nutrient cycling across Cambrian Stages 2–3 using two coeval drill cores from the Sichuan Basin, South China. Iron speciation, redox-sensitive trace metals, Mo/U, Re/Mo, and pyrite sulfur isotopes indicate predominantly anoxic bottom waters with recurrent shifts between ferruginous and euxinic conditions. Phosphorus-cycle indicators, organic carbon, nutrient-related trace metals, and weathering indices reveal parallel changes in nutrient inventories, productivity, and continental nutrient supply. During anoxic episodes, regeneration of reactive phosphorus and trace nutrients promoted productivity and organic-carbon export, strengthening oxygen consumption and sustaining anoxia. Conversely, intermittent oxygenation favoured phosphorus retention by iron oxides while temporarily expanding habitable marine environments. Our results suggest that the Stage 2–3 transition was characterized not by monotonic oxygenation, but by recurring redox–nutrient feedbacks. These oscillations may have generated repeated ecological windows that helped pace the Cambrian Explosion.