AIMS: Pavlik harness (brace) treatment is the cornerstone of management for infants with developmental dysplasia of the hip (DDH). However, there is wide variation in how the harness is discontinued, with some clinicians stopping immediately and others using gradual reduction ('weaning'), reflecting the absence of high-quality comparative evidence. WINDY (Weaning in INfant hip Dysplasia) is a multicentre randomized feasibility trial comparing a standardized weaning regimen with immediate cessation. The primary aim is to determine whether a definitive multicentre randomized controlled trial (RCT) is feasible. Secondary aims are to assess parental engagement, evaluate the acceptability and measurement properties of the Evaluation Measure for BRACe Experience (EMBRACE), and explore whether routinely collected Smart4NIPE data can be used for trial outcomes. METHODS: WINDY is a multicentre, parallel-group feasibility RCT with 1:1 allocation, stratified by site. Infants treated with a Pavlik harness who demonstrate ultrasound normalization (hip centred; α angle ≥ 60°) are eligible. Following consent, infants are randomized to either four weeks of night-time-only harness wear (minimum 10 hours per night) or immediate cessation. Follow-up is 12 weeks and aligned with routine care. Parents complete electronic questionnaires, including EMBRACE, at baseline, two, four, and six weeks post-randomization. Feasibility outcomes include recruitment, proportion randomized, parental engagement, and compliance. EMBRACE measurement properties and the feasibility of using routinely collected national data will also be assessed. DISCUSSION: This study will determine key feasibility parameters for a definitive multicentre RCT comparing harness weaning with immediate cessation in DDH, including recruitment, intervention acceptability, and parent-reported data completion. It will also provide further evaluation of the EMBRACE measure to support family-centred outcomes and assess whether routinely collected Smart4NIPE data can be used for trial outcome capture. As a feasibility study, analyses will be descriptive and will inform the design and delivery of a future definitive trial.