Summary Background Knowledge of the cost of illness of inflammatory bowel disease (IBD) is essential for health policy makers worldwide. Aim To assess the cost of illness of IBD from the societal perspective taking into account time trends and geographical differences. Methods A systematic review of all population‐based studies on cost of illness of IBD published in Embase, Medline, Web of Science and Google Scholar. Methodology of included studies was assessed and costs were adjusted to 2018 US dollars. Results Study methodologies differed considerably, with large differences in perspective, valuation method and population. For prevalent Crohn's disease (CD) cases in the last ten years annual healthcare costs were in Asia $4417 (range $1230‐$31 161); Europe $12 439 ($7694‐$15 807) and North America $17 495 ($14 454‐$20 535). For ulcerative colitis (UC), these were $1606 ($309‐$14 572), $7224 ($3228‐$9779) and $13 559 ($13 559‐$13 559). The main cost driver was medication, the cost of which increased considerably between 1985 and 2018, while outpatient and inpatient costs remained stable. IBD had a negative impact on work productivity. Annual costs of absenteeism for CD and UC were in Asia (with presenteeism) $5638 ($5638‐$5638) and $4828 ($4828‐$4828); Europe $2660 ($641‐$5277) and $2394 ($651‐$5992); North America $752 ($307‐$1303) and $1443 ($85‐$2350). Conclusion IBD societal cost of illness is increasing, driven by growing costs of medication, and varies considerably between continents. While biologic therapy was expected to decrease inpatient costs by reducing hospitalisations and surgery, these costs have not declined.