This dataset presents stable carbon isotope data measured on the epibenthic foraminifera Cibicidoides wuellerstorfi and Cibicides kullenbergi and the planktic foraminifera Globigerina bulloides at International Ocean Discovery Program Site U1540 (55° 8.47ʹ S, 114° 50.52ʹ W, 3580 m) during Marine Isotope Stage 11. The results are expressed in delta-notation (δ13C) with reference to the Vienna Pee Dee Belemnite (VPDB) standard. Full replicates were conducted to determine the 1σ-uncertainty of the analyses. The samples were measured with a Thermo Fisher Scientific MAT 253 isotope ratio mass spectrometer coupled to a Kiel IV carbonate preparation device at the Leibniz Laboratory for Radiometric Dating and Stable Isotope Research at Kiel University (Kiel, Germany).