This dataset includes stable oxygen isotope (δ¹⁸O ‰ V-SMOW) data and reconstructed Sea Surface Temperatures (SST) based on foraminiferal Mg/Ca measured on Globigerenoides ruber (pink variety) covering the last deglacial period (20 to 10 ka). Raw Mg/Ca data were converted to SSTs using the species-specific calibration provided by Dekens et al. (2002; doi:10.1029/2001GC000200). Combined stable oxygen isotope data and Mg/Ca based SSTs were used to calculate ice-volume free seawater (δ¹⁸Oivf-sw). Foraminiferal species G. ruber (p) were sampled from sediment Gravity Core M125-35-3 retrieved during research cruise M125 (RV METEOR) in 2016. Core M125-35-3 is located off south western Brazil in the tropical western South Atlantic in the pathway of the tropical warm southward-flowing Brazil Current.