Background: The choice of treatment for Crohn’s disease (CD) and ulcerative colitis (UC) depends among other factors, disease severity. Patients with moderate-to-severe disease should be prescribed biologic response modifiers (biologics), according to guidelines. This study aims to explore the treatment patterns of patients diagnosed with CD and UC between 2003 and 2015 that were treated with biologics in Denmark between the years 2003 and 2016. Methods: This national register study included patients diagnosed between 2003 and 2015, identified in the Danish National Patient Registry. Biologic therapies available during the study period were infliximab, adalimumab, vedolizumab and golimumab. The share of patients initiating and receiving biologic treatment in each year was estimated. Additionally, the time from IBD diagnosis to first biologic treatment and time between treatments was calculated. Results: Among 10,302 CD patients and 22,144 UC patients, 28.5% of CD patients and 11.3% of UC patients received treatment with biologics during the study period, with an increasing trend in the number of patients initiating treatment with biologics each year. About 46% of CD patients and 45% of UC patients received their first biologic treatment within the first year after IBD diagnosis. About 57–68% of CD and UC patients received treatment with their second line biologic within 2 months of the last treatment of their first line. Conclusions: The number of patients initiating biologic treatments after diagnosis increased throughout the study period. Most patients diagnosed with CD and UC are receiving biologic treatments relatively soon after their diagnosis.