ABSTRACT Introduction Patient and public involvement (PPI) is increasingly recognised as a vital component of health research, promoting inclusivity, relevance and impact. While PPI is well‐integrated into primary research, its role in secondary data analysis, where researchers work with pre‐existing data, remains underexplored. This targeted review aims to assess the prevalence, characteristics, and evolution of PPI in secondary data analysis studies, with a focus on articles published in The British Medical Journal (The BMJ) across selected years. Methods and Analysis This targeted literature review will examine original research articles published in The BMJ in 2014, 2019, and 2024. These years were selected to capture trends before and after the journal's 2015 mandate requiring PPI statements. Studies will be included if they utilise secondary data to address original research questions. A comprehensive search strategy using PubMed and a defined set of keywords related to secondary data will be employed. Articles will be screened independently by two reviewers at both title/abstract and full‐text stages. Data extraction will focus on study characteristics, PPI inclusion and outcomes influenced by PPI. Quantitative analysis will assess the prevalence and trends of PPI, while qualitative description of PPI statements will be used to summarise current practice and identify successful, effective practices. A representative sample of reviewed PPI statements will be shared in text and audio formats with six public contributors, who will assess them using a Likert scale and provide feedback on good and poor PPI practices during a facilitated meeting. Ethics and Dissemination As this review involves only published literature, ethical approval is not required. Findings will be disseminated through peer‐reviewed publication, academic conferences and community engagement events to inform best practices and promote meaningful PPI in secondary data research. Patient and Public Involvement Six public contributors will be involved in the review process, ranking PPI statements and providing feedback on the level of PPI input to the studies as well as the level of reporting in the articles (detailed in Section 3.4). Additionally, two public contributors reviewed and are co‐authors on this protocol, and we will invite another three public contributors to review any subsequent publications or materials produced by this review. We will adhere to the UK Standards for Public Involvement, ensuring we provide adequate support and inclusive opportunities for public contributors (e.g., by sending materials in text and audio formats in advance of meetings) and including them as co‐authors where appropriate to amplify their voices and maximise their impact on the project. Public contributors will be reimbursed in accordance with NIHR INVOLVE guidelines.