INTRODUCTION: Breast cancer has become the most common cancer worldwide. Various types of mindfulness-based interventions (e.g., mindfulness-based cognitive therapy, mindfulness-based stress reduction) have been conducted in different delivery methods (including face to face and internet delivered) to help patients with breast cancer mitigate their depression. However, at present, there are no studies that compare the effectiveness of all these types and deliveries of mindfulness-based interventions. Therefore, this protocol aims to conduct a systematic review and network meta-analysis to assess the effectiveness of various types and deliveries of mindfulness-based interventions in mitigating depression in patients with breast cancer. METHODS: This protocol is according to the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). The electronic databases, including PubMed, Web of Science, the Cochrane Library, Embase, Google Scholar, The China National Knowledge Infrastructure and OpenGrey, will be comprehensively retrieved for related randomised controlled trials (RCTs) from inception to December 2023. Two reviewers will independently assess the risk of bias using the Cochrane Risk of Bias Tool for Randomised Trials 2.0 (RoB 2.0). The network meta-analysis will be performed using the STATA V.16.0, and the assessment of heterogeneity, inconsistency, publication bias, evidence quality, subgroup analyses and sensitivity analyses will be conducted. ETHICS AND DISSEMINATION: This protocol does not require approval from an ethics committee as it is based on previous research findings. The results will be disseminated via peer-reviewed publications. PROSPERO REGISTRATION NUMBER: CRD42024495996.