This dataset contains dissolved neodymium (Nd) concentrations and radiogenic Nd isotope compositions from full water-column seawater profiles collected in the South Pacific Ocean during the GEOTRACES section GP21 (Chile to New Caledonia) aboard R/V SONNE (cruise SO289) between 23 February and 4 April 2022.Between 10 and 40 L of seawater were collected using 10 L Niskin bottles mounted on a stainless-steel CTD rosette. Beginning at Station 18, an additional 40 L of surface seawater was collected using a trace-metal-clean tow-fish to enable Nd isotope measurements at expected low concentrations.Samples for Nd isotope analysis were pre-concentrated onboard by coprecipitation with Fe hydroxide and later purified in the home laboratory before analysis by MC-ICP-MS (Thermo Neptune Plus). Nd concentrations were determined from 1 L acidified seawater aliquots spiked with a ¹⁵⁰Nd spike, processed via Fe-hydroxide coprecipitation and AG 50W-X8 cation exchange purification, and measured by isotope-dilution MC-ICP-MS with external reproducibility better than 0.2%.