In May 2022, 2 surface water and 7 bottom water samples were collected with a Sea-Bird CTD rosette water sampler during the cruise MSM107 from the Northwest Irish Shelf. These water samples were first filtered through 0.4 μm glass fibre filters to remove particles on broad, from which dissolved organic matter (DOM) was extracted using solid-phase extraction (SPE). The SPE extracted DOM (SPE-DOM) were analyzed for 13C and 14C compositions using an isotope ratio mass spectrometer and a mini carbon dating system (MICADAS), respectively. The SPE-DOM were also analyzed for molecular composition using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) (doi:10.1594/PANGAEA.969105). Based on these analyses, we aim to understand the distribution pattern, dynamics, and transformation of DOM during its downslope transport, confirming the significance of DOC exported by lateral transport in the ocean's carbon cycle. Detailed dataset interpretation can be found in Wei et al. (2024).