Abstract. Few Earth system models adequately represent the unique permafrost soil biogeochemistry and its respective processes; this significantly contributes to uncertainty in estimating their responses, and that of the planet at large, to warming. Likewise, the riverine component of what is known as the \u201cboundless carbon cycle\u201d is seldom recognised in Earth system modelling. The hydrological mobilisation of organic material from a \u223c1330\u20131580\u2009PgC carbon stock to the river network results in either sedimentary settling or atmospheric \u201cevasion\u201d, processes widely expected to increase with amplified Arctic climate warming. Here, the production, transport, and atmospheric release of dissolved organic carbon (DOC) from high-latitude permafrost soils into inland waters and the ocean are explicitly represented for the first time in the land surface component (ORCHIDEE) of a CMIP6 global climate model (Institut Pierre Simon Laplace \u2013 IPSL). The model, ORCHIDEE MICT-LEAK, which represents the merger of previously described ORCHIDEE versions MICT and LEAK, mechanistically represents (a)\u00a0vegetation and soil physical processes for high-latitude snow, ice, and soil phenomena and (b)\u00a0the cycling of DOC and CO2, including atmospheric evasion, along the terrestrial\u2013aquatic continuum from soils through the river network to the coast at 0.5 to 2\u2218 resolution. This paper, the first in a two-part study, presents the rationale for including these processes in a high-latitude-specific land surface model, then describes the model with a focus on novel process implementations, followed by a summary of the model configuration and simulation protocol. The results of these simulation runs, conducted for the Lena River basin, are evaluated against observational data in the second part of this study.