INTRODUCTION: Chronic pain is a common symptom significantly affecting the quality of life of breast cancer survivors. Despite the achievement of pharmacological interventions, the barriers associated with this approach such as inaccessibility, misuse and side effects drive research into effective non-pharmacological interventions to improve chronic pain management, quality of life, anxiety and depression. Breathing exercise (BE) can be a promising option, but research evidence is sparse. This pilot study aims to examine the feasibility and preliminary effect of using an evidence-based BE intervention for chronic pain management in breast cancer survivors. METHOD AND ANALYSIS: This study will be a two-parallel-arm, open-labelled, phase II randomised controlled trial with 1:1 allocation. Seventy-two participants will be recruited from a tertiary hospital in China and randomly allocated to either a BE intervention group (n=36) or a control group (n=36). The participants in the intervention group will receive the usual care, a pain information booklet and a 4-week self-administered BE intervention; the participants in the control group will receive the usual care and the pain information booklet only. The assessment will be conducted at three time points: baseline (week 0), immediately after the intervention completion (week 5) and 4 weeks after the intervention completion (week 9). The primary outcomes will be the acceptability and feasibility assessment of the study protocol and methodological procedures. The secondary outcomes will be the effects of BE on pain, quality of life, anxiety and depression in breast cancer survivors. Descriptive statistics will be applied to present the primary outcomes and the Generalised Estimating Equation Model will be utilised to analyse the clinical outcomes. ETHICS AND DISSEMINATION: This study has received ethical approvals from the Human Research Ethics Committee at Charles Darwin University (H21089) and the Clinical Trial Ethics Committee at the Affiliated Hospital of Southwest Medical University (KY2022107). Findings from this study will be presented at academic conferences and submitted to peer-reviewed journals for publication. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT05257876.