During the Cambrian Explosion, episodic radiations of major animal phyla occurred in concert with repeated coupled carbon-sulfur isotope excursions. These isotope patterns are thought to reflect oscillations in atmospheric and shallow-marine O-2, which promoted animal diversification events. However, the driver for oxygenation pulses is unclear. Here we show that these synchronous carbon-sulfur isotope cycles and marine oxygenation pulses can be driven by long-period orbital forcing through effects on continental weathering and nutrient delivery. The impact of orbital forcing is explored using a combined climate-biogeochemical model. When forced with latitudinally-resolved insolation signals, the model produces long-term variations in nutrient weathering and carbon burial, which reproduces the co-variation of carbon-sulfur isotopes. We conclude that the oxygen-driven evolutionary changes in the early Cambrian can be explained by recurrent nutrient inputs to the ocean, resulting from climate change caused by long-period orbital cycles.