IntroductionOur aim is to investigate whether a shortened digital self-care intervention is non-inferior to, and cost-effective compared with, a comprehensive and therapist-guided cognitive behavioural therapy treatment for atopic dermatitis (AD).Methods and analysisThis is a single-blind, randomised clinical non-inferiority trial at Karolinska Institutet, a medical university in Stockholm, Sweden. We will recruit 174 adult participants with AD through self-referral. Participants will be randomised 1:1 to the two experimental conditions. Participants randomised to guided care will receive internet-delivered cognitive behavioural therapy for 12 weeks. Participants randomised to digital self-care will have access to this self-guided intervention for 12 weeks. At post-treatment (primary endpoint), non-inferiority will be tested and resource use will be compared between the two treatment groups. Cost-effectiveness will be explored at 1-year follow-up. Potential mediators will be investigated. Data will be analysed intention to treat. We define non-inferiority as a three-point difference on the primary outcome measure (Patient-oriented Eczema Measure). Recruitment started in November 2022.Ethics and disseminationThis study is approved by the Swedish ethics authority (reg. no 2021-06704-01) and is preregistered at ClinicalTrials.gov. The study will be reported according to the Consolidated Standards of Reporting Trials statement for non-pharmacological trials. The results of the study will be published in peer-reviewed scientific journals and disseminated to patient organisations and media.Trial registration number NCT05517850.