Background: Acne is the most frequent adverse event associated with upadacitinib treatment in patients with moderate-to-severe atopic dermatitis. Objective: To characterize the adverse event of acne associated with upadacitinib. Methods: This was a post hoc integrated analysis of 3 phase 3 randomized, double-blind, placebo-controlled trials of upadacitinib, alone (NCT03569293 and NCT03607422) or in combination with topical corticosteroids (NCT03568318). Data included were from the 16-week placebo-controlled period. Results: Over 16 weeks, 84 of 857 (9.8%), 131 of 864 (15.2%), and 19 of 862 (2.2%) patients randomized to receive upadacitinib 15 mg, upadacitinib 30 mg, and placebo, respectively, experienced acne. All cases of acne, except 1, were mild/moderate in severity; 2 patients discontinued treatment due to moderate acne. Acne occurred at higher rates among younger, female, and non-White patients. Acne required no intervention in 40.5% and 46.6% of patients receiving upadacitinib 15 and 30 mg, respectively; most remaining cases were managed with topical antibiotics, benzoyl peroxide, and/or retinoids. Acne also had no impact on patient-reported outcomes. Limitations: This study was relatively short in duration and had a small patient population. Conclusions: Acne associated with upadacitinib for atopic dermatitis treatment is usually mild/moderate in severity and managed with topical therapies or no intervention.