Proglacial braided river systems discharge large volumes of meltwater from ice sheets and trans-port coarse-grained sediments from the glaciated areas to the oceans. Here, we test the hypothesisif high-energy hydrological events can leave distinctive signatures in the sedimentary record ofbraided river systems. We characterize the morphology and infer a mode of formation of a25 km long and 1–3 km wide Early Pleistocene incised valley recently imaged in 3-D seismicdata in the Hoop area, SW Barents Sea. The fluvial system, named Bjørnelva River Valley, carved20 m deep channels into Lower Cretaceous bedrock at a glacial paleo-surface and deposited28 channel bars along a paleo-slope gradient of∼0.64 m km−1. The landform morphologiesand position relative to the paleo-surface support that Bjørnelva River Valley was formed inthe proglacial domain of the Barents Sea Ice Sheet. Based on valley width and valley depth, wesuggest that Bjørnelva River Valley represents a braided river system fed by violent outburstfloods from a glacial lake, with estimated outburst discharges of∼160 000 m3s−1. The morpho-logical configuration of Bjørnelva River Valley can inform geohazard assessments in areas at riskof outburst flooding today and is an analogue for landscapes evolving in areas currently coveredby the Greenland and Antarctic ice sheets.