IntroductionKey to improving outcomes for patients with multimorbidity is increasing mobility through prescription of a physical activity programme, but this can be difficult to achieve in acute hospital settings. One approach that would assist physiotherapists to increase levels of physical activity is delegation of rehabilitation to allied health assistants. We aim to conduct a randomised controlled trial to determine the feasibility of an allied health assistant providing daily inpatient mobility rehabilitation for patients with multimorbidity.Methods and analysisUsing a parallel group randomised controlled design, participants will be allocated to allied health assistant mobility rehabilitation or physiotherapist mobility rehabilitation. Adult inpatients (n=60) in an acute hospital with a diagnosis of multimorbidity who walked independently preadmission will be included. The experimental group will receive routine mobility rehabilitation, including daily mobilisation, from an allied health assistant under the supervision of a physiotherapist. The comparison group will receive routine rehabilitation from a physiotherapist. Feasibility will be determined using the following areas of focus in Bowen’s feasibility framework: Acceptability (patient satisfaction); demand (proportion of patients who participate); implementation (time allied health assistant/physiotherapist spends with participant, occasions of service); and practicality (cost, adverse events). Staff involved in the implementation of allied health assistant rehabilitation will be interviewed to explore their perspectives on feasibility. Secondary outcomes include: Physical activity (daily time spent walking); daily mobilisation (Y/N); discharge destination; hospital readmission; falls; functional activity (Modified Iowa Level of Assistance Scale); and length of stay. Descriptive statistics will be used to describe feasibility. Secondary outcomes will be compared between groups using Poisson or negative binomial regression, Cox proportional hazards regression, survival analysis, linear regression or logistic regression.Ethics and disseminationEthics approval was obtained from Peninsula Health (HREC/97 431/PH-2023). Findings will be disseminated in peer-reviewed journals and conference presentations.Trial registration numberAustralian and New Zealand Clinical Trial Registry ACTRN12623000584639p.