Abstract Background Frailty is characterised by increased vulnerability to falls, disability, hospitalisation and care home admission. However, it is relatively reversible in the early stages. Older people living with frailty often have multiple health and social issues which are difficult to address but could benefit from proactive, person-centred care. Personalised care planning aims to improve outcomes through better self-management, care coordination and access to community resources. Methods This feasibility cluster randomised controlled trial aims to recruit 400 participants from 11 general practice clusters across Bradford and Leeds in the north of England. Eligible patients will be aged over 65 with an electronic frailty index score of 0.21 (identified via their electronic health record), living in their own homes, without severe cognitive impairment and not in receipt of end of life care. After screening for eligible patients, a restricted 1:1 cluster-level randomisation will be used to allocate practices to the PROSPER intervention, which will be delivered over 12 weeks by a personal independence co-ordinator worker, or usual care. Following initial consent, participants will complete a baseline questionnaire in their own home including measures of health-related quality of life, activities of daily living, depression and health and social care resource use. Follow-up will be at six and 12 months. Feasibility outcomes relate to progression criteria based around recruitment, intervention delivery, retention and follow-up. An embedded process evaluation will contribute to iterative intervention optimisation and logic model development by examining staff training, intervention implementation and contextual factors influencing delivery and uptake of the intervention. Discussion Whilst personalised care planning can improve outcomes in long-term conditions, implementation in routine settings is poor. We will evaluate the feasibility of conducting a cluster randomised controlled trial of personalised care planning in a community population based on frailty status. Key objectives will be to test fidelity of trial design, gather data to refine sample size calculation for the planned definitive trial, optimise data collection processes and optimise the intervention including training and delivery. Trial registration ISRCTN12363970 – 08/11/18.