Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Cardiometabolic diseases, such as cardiovascular diseases (CVD) and diabetes mellitus (DM), represent a global health issue, causing significant premature mortality and disability. Blue-collar workers, who often face a higher exposure to risk factors (eg, smoking, poor diet, and lack of physical activity), are particularly vulnerable to these diseases. Workplace health promotion plays a crucial role in mitigating this risk, yet the scope and the characteristics of interventions targeting this specific workforce remain unclear. Objective: The objective of this scoping review will be to assess the extent and characteristics of workplace health promotion interventions aimed at preventing cardiometabolic diseases and their risk factors in blue-collar workers. Methods: The review will follow the JBI methodology for scoping reviews. A search of MEDLINE, Scopus, Embase, and the Cochrane Database as well as grey literature will be conducted. The search strategy is designed to capture relevant studies published since 2014 in English, Spanish, Italian, and Polish. Eligible study designs include experimental design (eg, randomized controlled trials), observational studies (eg, longitudinal studies), qualitative research, and mixed-method approaches as well as other formats present in grey literature (eg, reports). This review will include studies focusing on health promotion interventions involving adult blue-collar workers (aged ≥18 years) currently employed, with at least 60% of participants being blue-collar employees. The interventions of interest are workplace health promotion strategies targeting CVD, DM, or their risk factors, such as hypertension, obesity, and smoking. Each paper retrieved will be screened for inclusion by at least 2 reviewers. Disagreements between the reviewers will be resolved through discussion with the other reviewers. Studies focusing on noninterventional contexts, mental health, or ergonomic safety will be excluded. Data will be extracted and analyzed using qualitative and quantitative methods, with a focus on intervention types, participant characteristics, and outcomes. Results: The study began in March 2024 and the full scoping review report is expected to be ready in September 2025. Conclusions: The scoping review presented in this protocol can contribute to filling the knowledge gap by mapping the current state of workplace health promotion interventions aimed at preventing CVD and DM and modifying relevant risk factors in the blue-collar workers’ group. Trial Registration: Open Science Framework hdrq4; https://osf.io/hdrq4