Background: Economic burden studies can provide insights into the drivers leading to increasing healthcare costs. It can also provide a more holistic view of how diseases impact the welfare of patients and their families. Having concrete estimates of the economic burden across multiple diseases can help policymakers determine which diseases are economically more burdensome. This study aimed to review and summarise comprehensively economic burden studies across multiple diseases in the Nordic countries between 2000 and 2020. Methods: According to the 2020 PRISMA statement, a systematic literature review was conducted in PubMed, CINAHL, Academic Search Premier and Global Health databases using key terms related to the economic burden of any disease in Denmark, Finland, Greenland, Iceland, Norway and Sweden. Grey literature was also reviewed. Results: A total of 10,050 potential titles and abstracts were identified and screened, and 254 full-text papers that met the inclusion criteria were evaluated by two independent reviewers. Of these, 119 articles were included in a qualitative synthesis. Twenty-nine had clearly defined comparison groups, thus able to attribute the costs to the disease. Large variations concerning methodology and cost components were noted. Across diseases, the economic burden ranged from EUR 1668 per patient annually for chronic obstructive pulmonary disease to EUR 93,041 for multiple sclerosis. However, estimates varied widely, even within each disease. Conclusions: Our review highlights the need for more comparable economic burden studies. Future studies should focus on applying robust methodology and homogeneous cost-reporting methods to inform policymakers about which diseases are economically more burdensome.