The Iberian Margin, located in the mid-latitude North Atlantic at the western edge of Europe, is a key region for reconstructing past climate and oceanographic variability. As part of the PTDC/CTA-CLI/2884/2021 ICW3P project, this study presents a dinoflagellate cyst record from an inner-shelf sediment core collected west of the Tagus River mouth (core POS-26B). The western Portuguese margin represents the northern limit of the Canary Current upwelling system, which is characterized by seasonal, wind-driven upwelling from May to September.The gravity core was retrieved during the Poseidon cruise PO287 in 2002 and provides a high-resolution dataset covering the last millennium, from the Little Ice Age to present-day. The dataset includes raw counts of dinoflagellate cysts, distinguishing heterotrophic from autotrophic taxa, together with depth information for each sample. 16 samples have been analysed using a microscope were analyzed for their palynological contents using a transmitted light microscope at 500× to 1,000× magnification.