Abstract Atopic dermatitis (AD) is characterized by intense itch and symptoms that adversely impact quality of life (QoL). Upadacitinib is a selective Janus kinase-1 inhibitor approved for moderate-to-severe AD. We assessed the effect of once daily oral upadacitinib (15 or 30 mg), with or without concurrent topical corticosteroid treatment, on patient-reported outcomes for adults and adolescents with moderate-to-severe atopic dermatitis during the double-blind, placebo-controlled phase 3 clinical trials, Measure Up 1 (NCT03569293), Measure Up 2 (NCT03607422) and AD Up (NCT03568318). Assessments included itch (Worst Pruritus Numerical Rating Scale), skin pain and symptom severity (AD Symptom Scale), symptom frequency (Patient Oriented Eczema Measure) and sleep, daily activities and emotional state (AD Impact Scale). Post hoc analysis of 2240 adults and 344 adolescents randomized patients was performed. By Week 2, more patients receiving upadacitinib achieved a clinically relevant response in itch, skin pain, symptom severity, symptom frequency, sleep, daily activities and emotional state vs. placebo across studies among adults (upadacitinib 15 mg: 30.8–87.3%; upadacitinib 30 mg: 38.0–89.9%; placebo: 2.1–43.1%; nominal P < 0.001 for all comparisons) and adolescents (upadacitinib 15 mg: 19.4–82.9%; upadacitinib 30 mg: 35.3–97.6%; placebo: 0–41.0%; nominal P < 0.05 for 37/42 comparisons). These trends continued through week 16 where response rates for all outcomes improved with upadacitinib vs. placebo in adults (upadacitinib 15 mg: 42.9–80.4%; upadacitinib 30 mg: 60.9–84.6%; placebo: 10.1–38.1%; nominal P < 0.001 for all comparisons) and adolescents (upadacitinib 15 mg: 33.3–78.0%; upadacitinib 30 mg: 50.0–85.7%; placebo: 2.8–43.6%; nominal P < 0.05 for 41/42 comparisons). These findings highlight the rapid, sustained efficacy of once daily oral upadacitinib in improving symptom burden and QoL in adults and adolescents with moderate-to-severe AD.