Self-harm in young people is a growing concern and reducing rates a global priority. Rates of self-harm documented in general practice have been increasing for young people in the UK in the last two decades, especially in 13-16-year-olds. General practitioners (GPs) can intervene early after self-harm but there are no effective treatments presently available. We developed the GP-led COPING intervention, in partnership with young people with lived experience and GPs, to be delivered to young people 16-25 years across two consultations. This study aims to examine the feasibility and acceptability of conducting a fully powered effectiveness trial of the COPING intervention in NHS general practice. This will be a mixed-methods external non-randomised before-after single arm feasibility study in NHS general practices in the West Midlands, England. Patients aged 16-25 years who have self-harmed in the last 12 months will be eligible to receive COPING. Feasibility outcomes will be recruitment rates, intervention delivery, retention rates, and completion of follow-up outcome measures. All participants will receive COPING with a target sample of 31 with final follow-up data collection at six months from baseline. Clinical data such as self-harm repetition will be collected. A nested qualitative study and national survey of GPs will explore COPING acceptability, deliverability, implementation, and likelihood of contamination. Brief GP-led interventions for young people after self-harm are needed to address national guideline and policy recommendations. This study of the COPING intervention will assess whether a main trial is feasible. ISRCTN (ISRCTN16572400; 28.11.2023).