The moderate impact of rapid global warming on oceanic redox and biodiversity during the Paleocene-Eocene thermal maximum (PETM; similar to 55.9 Ma) contrasts with other hyperthermal events in Earth's history, and remains mostly unexplained. Here, we use lithium isotope (delta Li-7) proxy and Earth system model simulations to reconstruct continental weathering regimes during the PETM. Negative delta Li-7 excursions of 3-4 parts per thousand in shallow-marine carbonates suggests globally increased erosion rates and decreased weathering intensities. Further, large negative delta Li-7 excursions of 4-5 parts per thousand in siliciclastic successions reflect enhanced accumulation of detrital clays exhumed from previous clay-rich sedimentary rocks, rather than those from weathering of igneous rocks. Changes in continental weathering regimes and associated flux of nutrients to oceans provide an explanation to the muted increase in oceanic anoxia and overall biodiversity loss during the PETM. The concomitant increases in physical erosion and clay delivery also enhanced organic carbon burial efficiency, permitting rapid return of global climate to pre-perturbation state.