Sulfur isotopes in archaeological faunal collagen are increasingly used to reconstruct past climate and environment. Here we identify a major sulfur isotope excursion in Eurasian faunal collagen from the last 50,000 years, here termed the Late Pleniglacial Sulfur Excursion. Our analysis suggests this is linked to changing permafrost conditions, presenting the utility of faunal collagen δ34S as a proxy for permafrost dynamics, a critical component of the global carbon cycle.This dataset contains the sample information, radiocarbon dates, isotope data, and parameters for statistical tests performed as part of this study.