The Mesolithic burial from Brunstad, Vestfold, Eastern Norway, dating to c. 5900 cal BC, represents rare evidence of Mesolithic mortuary practice in Norway. While Mesolithic settlement finds are abundant in the region, evidence of mortuary ritual is virtually absent in the record. In this article we present the method and the results of the multidisciplinary excavation, on-site and in the laboratory. The challenging Brunstad find was excavated in two steps, and later reconstructed, involving osteology, 3D photogrammetry and conservation. Moreover, the burial is discussed in its local, regional and supra-regional context. While the inhumation of an adult individual in a flexed body position is rare in its regional context, it exhibits typical features known from Mesolithic graves in Scandinavia as well as from other parts of Europe. These include the shore-based island location and proximity to a settlement site, the body position, as well as certain features of mortuary ritual. In the light of Mesolithic mortuary practices in Scandinavia and the Baltic region, from where many Mesolithic graves are known, we suggest that Mesolithic hunter-gatherers in Eastern Norway and the Skagerrak region handled and disposed of their dead in various ways, some of which might not have left archaeological traces. We conclude that the Brunstad grave represents a distinct mode of burial at the time. Highlights-Rare inhumation sheds light on Mesolithic mortuary practice in Norway-Interdisciplinary two-step excavation allows reconstruction of flexed body position-Burial exhibits traits of hunter-gatherer graves across Europe-Site context gives insight into hunter-gatherer ritual and mobility-A distinct burial at its time