This dataset includes compound-specific stable carbon isotope (δ¹³C) values of long-chain n-alkanes (nC27–nC33) from the Holocene marine sediment core MDBT 561, collected on the southern Brazilian continental shelf. Individual n-alkanes were analyzed using gas chromatography–combustion–isotope ratio mass spectrometry (GC-C-IRMS). The compound-specific isotope data provide information on the sources and isotopic composition of terrigenous organic matter delivered to the shelf, supporting reconstructions of vegetation dynamics and continental hydrological variability during the Holocene.