A well-preserved stratigraphic record of the organic carbon isotopic composition across the Precambrian–Cambrian transition has been obtained from a sequence of entirely detrital rocks underlying the Lublin Slope, East European Platform, Poland. The observed δ13C pattern for organic carbon is comparable to isotope data determined for coeval carbonate platform sequences elsewhere. These results underline the truly global nature of these secular variations within the carbon cycle during the terminal Proterozoic and early Cambrian, largely independent of host lithology and facies. The direct combination of micropalaeontological and geochemical results from sedimentary organic matter allows a detailed interpretation of the isotope record as probably caused by secular changes in the net balance of burial and erosion rates of repositories of organic carbon. Furthermore, these variations appear to be directly correlatable with changes in the diversity and abundance of the biota and radiation/extinction events.