This dataset contains radiocarbon dating results of sediment cores from the Trunvel and Kerallé valleys, Brittany, North-West France. These analyses were carried out as part of the doctoral project Paleogeographic changes and coastal archaeological remains in Brittany during the Middle and Late Holocene: Contributions of a multidisciplinary and multi-scaled approach, with the aim of reconstructing the Holocene evolution of small estuarine systems on the North-West French coast.A total of 60 organic-rich samples were selected for AMS-¹⁴C dating. Samples were analyzed at the Laboratoire de Mesure du Carbone 14 (Saclay, France) and the Beta Analytic laboratory (Miami, USA). Measurements were performed on detrital fragments of halophilic plants where material was available. All conventional dates were calibrated with OxCal v.4.4.4 software (Bronk Ramsey, 2021) using the IntCal20 calibration curve (Reimer et al., 2020).