Here, we provide the results of the clumped isotope analyses of 24 biogenic carbonate samples, along with the results of carbonate reference materials (ETH1–4, Carrara, MuStd, Strauss) and equilibrated gases (25 °C and 1000 °C). Carbonate digestion at 90 °C and subsequent CO2 purification was done on an automated line connected to a ThermoFisher MAT 253 isotope ratio mass spectrometer. We present the raw isotope values calculated using both the [Gonfiantini/Santrock] and the [Brand]/IUPAC isotopic parameters. The raw data is projected onto the carbon dioxide equilibrium scale using the equilibrated gases and without applying any fractionation factor to the final values. Preparation methods and mass spectrometry analytics are further detailed in the associated files and the linked article.