This study presents a detailed soil organic carbon (SOC) inventory for two areas in the mountain periglacial zone of northern Patagonia (altitude range c. 1,400–2,100 m). We describe plant cover and soil profiles at twenty-seven sites representing the main land cover classes and landform types at and above the treeline. The mean SOC 0–100 cm storage is 2.31 kg C m⁻² for the combined study areas, which includes 69 percent of bare ground surfaces with negligible SOC stocks. If we consider the vegetated alpine belt only, mean SOC 0–100 cm storage increases to 6.96 kg C m⁻². Solifluction has resulted in areas with dense plant cover and deep soil profiles with mean SOC 0–100 cm of 17.1 to 18.3 kg C m⁻² and a maximum total stock of 51.5 kg C m⁻². Lowest SOC storages of 0.13 to 0.63 kg C m⁻² are found in bare and sparsely vegetated high-elevation areas with shallow and stony soils developed in patterned ground (stripes and sorted circles). Projected future increases in ambient temperature will likely result in an upward shift of the alpine vegetation belt with soil development, creating new areas of ecosystem carbon storage.