Background: Psoriasis is a common inflammatory skin disease associated with several immune-mediated inflammatory diseases (IMIDs); however, little is known of the chronology of disease development. Objective: To investigate the chronology of IMIDs relative to psoriasis. Methods: We utilized routinely collected data from Danish nationwide administrative registries to examine the occurrence of IMIDs in patients with psoriasis (n = 10,923) and general population controls (n = 109,230). Results: Approximately 20% of patients with psoriasis developed ≥1 IMID, with a 5-fold increased risk compared with the general population. Most IMIDs were diagnosed before psoriasis, except for psoriatic arthritis. Psoriasis was significantly associated with having multiple IMIDs (odds ratio 15.2, 95% confidence interval 11.6-20.0). Human leukocyte antigen B27 positivity was significantly more frequent among psoriasis patients. Limitations: Clinical measurements were unavailable. Conclusion: IMIDs occur frequently in patients with psoriasis and most are diagnosed before psoriasis. The observed chronology might represent important mechanisms of disease development.