Background Real-life data on long-term effectiveness and safety of dupilumab in atopic dermatitis patients are limited. Objective To study 52-week effectiveness and safety of dupilumab in a prospective multicenter cohort of adult patients with treatment-refractory atopic dermatitis. Methods Patients treated with dupilumab and participating in the Dutch BioDay registry were included. Clinical effectiveness and safety were evaluated. Results Two hundred ten atopic dermatitis patients were included. Mean percentage change in Eczema Area and Severity Index score after 16 weeks was –70.0% (standard deviation 33.2%) and further decreased to –76.6% (standard deviation 30.6%) by week 52. A greater than or equal to 75% improvement in the score was achieved by 59.9% of individuals by week 16 and by 70.3% by week 52. The most reported adverse effect was conjunctivitis (34%). Limited patients (17; 8.1%) discontinued dupilumab treatment. Limitations Because of the lack of a control group and observational design, factors of bias may have been induced. Conclusion Treatment with dupilumab resulted in a rapid improvement in clinical outcome measures, and effectiveness further improved during the 52-week follow-up period.