Previous studies demonstrated that delgocitinib ointment, a novel topical Janus kinase inhibitor, rapidly improved clinical signs and symptoms of atopic dermatitis (AD) in Japanese adult patients. We sought to evaluate the long‐term safety and efficacy of delgocitinib 0.5% ointment in a 52‐week study (QBA4‐2). Japanese patients aged 16 years or older with AD received delgocitinib 0.5% ointment b.i.d. for up to 52 weeks. Topical corticosteroids for the treatment of worsening of AD could be used at the investigators’ discretion during the treatment period. Safety end‐points included the incidence and severity of adverse events (AEs). Pooled safety analyses included the data from the other long‐term study (QBA4‐1). Efficacy end‐points included the percentage change from baseline in the modified Eczema Area and Severity Index (mEASI). A total of 506 patients were included in the pooled safety population. Overall, AEs were reported in 69.0% of patients; most AEs were mild and unrelated to delgocitinib ointment. The most common AE was nasopharyngitis, followed by contact dermatitis, acne, and application site folliculitis. No skin atrophy or telangiectasia was found at the application sites of delgocitinib ointment. Application site irritation symptoms were infrequent (<2%) and mild. The incidence of AEs did not increase over time, except for seasonal diseases. The improvement effects on AD as assessed by mEASI were maintained throughout the treatment period. Delgocitinib 0.5% ointment was well tolerated and effective when administrated to Japanese adult patients with AD for up to 52 weeks.