Mycorrhizal associations are essential to most plant life on earth. Cassiope tetragona is a circumpolar Arctic plant in the Ericaceae family, which has been reported to form ericoid mycorrhiza as well as ectomycorrhiza, though little is known about the functions and identities of these fungal partners. In light of climate change, it is essential to unravel these gaps in our knowledge as we attempt to predict how the Arctic will respond. In this study, the fungal root associates of C. tetragona from Svalbard were investigated using high-throughput sequencing to characterize the community, determine the type of mycorrhizal association, and to evaluate the effects of artificial warming by open-top chambers (OTCs). The root fungal community of C. tetragona was dominated by basidiomycetes which mainly function as ectomycorrhizal or saprotrophs. There was a low proportion of the root fungal community which could be identified as ericoid mycorrhizal. This indicates that C. tetragona may not form ericoid mycorrhiza at this location or is forming mycorrhiza with unconfirmed ericoid mycorrhiza lineages, such as members of the Sebacinales, Mycena, or Clavaria. There was only a slight effect of warming on the root-associated fungal community, when the variation due to location was removed. Another environmental factor is most likely masking the warming effects, or the warming period (eight years) was not sufficiently long to see a response in the root fungal community. The need for more extensive studies on the fungal associations of C. tetragona is emphasized.