The Cambrian Explosion witnessed the rapid radiation of nearly all animal phyla in three distinct evolutionary phases. Recent studies from South China have proposed that the prevalence of suboxic environments in the Terreneuvian shallow ocean facilitated the diversification of lophotrochozoans with relatively low oxygen requirements during the second phase of the Cambrian Explosion. To further test this hypothesis, we present a high-resolution δ¹⁵N record from the inner-ramp Penglaiba section in the Aksu area, Tarim Basin, an independent paleocontinent with exceptionally well-preserved Terreneuvian successions. Our results document a progressive decrease in δ¹⁵N values from > +4‰ to < +1‰ in the lower unit of the Yuertusi Formation, followed by stable δ¹⁵N values of ~+3‰ in the upper unit. This isotopic pattern records a two-stage redox history for the shallow Tarim Basin, with progressive intensification of water-column deoxygenation succeeded by partial reoxygenation. Integrated with published regional δ¹⁵N data, our results demonstrate the existence of a persistent depth-dependent redox gradient throughout the Terreneuvian, with denitrification intensity decreasing systematically from anoxic deep-basin to suboxic inner-ramp environments. These findings provide cross-basin validation for the hypothesis that stepwise oxygenation of the shallow ocean modulated the multi-phase evolutionary trajectory of metazoans during the Cambrian Explosion.