This dataset contains foraminifera-bound nitrogen isotope (FB-δ¹⁵N) measurements from Ocean Drilling Program (ODP) Site 165-999 (12°44.6′N, 78°44.5′W; 2,828 m water depth) in the western tropical Atlantic. The dataset includes sample labels, composite depths, age assignments, FB-δ¹⁵N measurements of Trilobatus sacculifer and Globigerinoides ruber, analytical precision, and nitrogen contents. The samples span the late Pliocene to early Pleistocene (approximately 3.6–2.0 Ma) and the last 160 kyr. The measurements were generated to document temporal changes in upper-ocean nitrate nitrogen isotopes in the western tropical Atlantic. Foraminifera-bound nitrogen isotope analyses were performed following oxidative cleaning of planktic foraminiferal tests and isotopic analysis using the denitrifier method, as described in the associated publication. All foraminifera-bound δ¹⁵N and N content are measured by the persulfate–denitrifier method on the "Sigbench," a custom-built continuous-flow N₂O extraction and purification system coupled to a Thermo Fisher Scientific MAT 253 Plus isotope ratio mass spectrometer (method according to Sigman et al. (2001), Martínez-García et al. (2022), and Moretti et al. (2023)).