This dataset compiles descriptive information (i.e., sample metadata and chronostratigraphic details), whole-rock major and trace element concentrations, and Sr–Nd isotope compositions for 400 onshore and 55 offshore volcanic samples from the ocean island of El Hierro (Canary Islands). Geochemical data are derived from 42 independent data sources, including peer-reviewed scientific publications, PhD theses, and institutional reports produced between 1977 and 2025. Sample metadata, chronostratigraphic information, and analytical data were compiled and digitised manually from the original sources. For onshore samples, coordinates were extracted directly from the references when available, or reconstructed from sample and locality information, detailed outcrop descriptions or schematic drawings, and original field maps when absent. For offshore dredged samples, coordinates were estimated by georeferencing published dredge-haul trajectories. For offshore samples collected during the 2011–2012 submarine eruption and encountered floating at the sea surface, the geographic coordinates of the submarine cone were systematically assigned. To preserve the legacy information, volcanic unit assignments reported in the literature are retained for traceability, whereas samples are reassigned when their original volcanic units are no longer in use to one of the following volcanic units: submarine stage, Tiñor volcano (1.12–0.88 Ma), El Golfo volcano (545–176 ka), and rift volcanism (<158 ka). Samples classified within the rift volcanism unit are further subdivided into three subunits: pre-Holocene rift volcanism, Holocene rift volcanism, and 2011–2012 submarine eruption, following a recently published chronostratigraphic reconstruction of the Holocene volcanism on El Hierro. Throughout the compilation process, spatial information, volcanic unit assignments, and geochemical data have been cross-checked against geological maps, current stratigraphic and geomorphological criteria, and original descriptions to ensure internal consistency. Overall, this compilation highlights the scientific value of systematically curated legacy geochemical data and offers new opportunities for advancing the understanding of the magmatic system beneath El Hierro island.