BACKGROUND: Obstructive sleep apnoea (OSA) is a common and modifiable risk factor for atrial fibrillation (AF), yet it remains frequently unrecognised and undertreated. Despite guideline recommendations to consider OSA screening, no consensus exists on optimal strategies. The VIR-SAAF (VIRtual national study with home Sleep Apnea investigation in patients with Atrial Fibrillation) trial investigates whether home-based OSA screening and referral for potential treatment improve quality of life, physical activity and AF-related outcomes compared with standard care. METHODS AND ANALYSIS: VIR-SAAF is a national, investigator-initiated, decentralised randomised clinical trial enrolling adults with paroxysmal or persistent AF across Denmark. Participants are randomised 2:1 to home-based screening for OSA or to no screening. The trial is conducted entirely remotely using a purpose-built mobile application that supports electronic consent, digital questionnaires, rhythm monitoring, activity tracking and real-time communication with investigators. This design allows all study procedures, including device delivery, data collection and follow-up, to be completed without in-person visits, enabling large-scale participation across geographical regions. The primary outcome is the between-group difference in change from baseline to 18 weeks in quality of life, assessed using the Atrial Fibrillation Effect on QualiTy-of-life questionnaire. VIR-SAAF is the first randomised trial to evaluate OSA screening itself as an intervention in AF. The fully decentralised design will generate novel evidence on whether systematic home-based OSA screening can improve patient-centred outcomes. ETHICS AND DISSEMINATION: The study has been approved by the Danish National Committee on Health Research Ethics (approval number: 2402591). All participants provide electronic informed consent prior to enrolment. Results will be disseminated through peer-reviewed publications and presentations at national and international scientific conferences. TRIAL REGISTRATION NUMBER: NCT06618417.