Here we present planktonic foraminifera Globigerinoides ruber (white) s.s. Mg/Ca ratios (mmol/mol) obtained in marine sediment core NAP63-1 (24.8384°S, 44.3187°W, 842 m water depth, 224 cm sediment recovery) retrieved with the aid of a piston corer from the SW Atlantic upper slope. For Mg/Ca analyses, between 30-50 shells of G. ruber (white) s.s. tests were picked from the 250–300 µm size fraction and analyzed with a Thermo Scientific iCap Q quadrupole ICP-MS. Mg/Ca ratios were applied to obtain SW Atlantic sea-surface temperature estimates over the last 50 kyr. Our results highlight the relationship between the SW Atlantic sea-surface conditions and Atlantic Meridional Overturning Circulation strength.