OBJECTIVES: This systematic review and meta-analysis aimed to assess sedentary work's contribution to breast cancer risk quantitatively using thorough research articles. METHODS: We performed a meta-analysis using a registered protocol in PROSPERO (registration number: CRD42020204629). Literature from PubMed, Embase, and Cochrane involving sedentary work and breast cancer risk was reviewed. We calculated the overall pooled risk ratios (RRs) and 95% CI with a random-effect model from the included studies. Furthermore, we performed stratified analyses by characteristics of studies. RESULTS: Thirty-one studies (13 cohort studies and 18 case-control studies) were included in the analysis. The overall effect of the pooled analysis was an RR of 1.16 (95% CI 1.08-1.23). The results were 1.20 (95% CI 1.10-1.30) and 1.12 (95% CI 1.02-1.23) for cohort and case-control studies. The effect of sedentary work did not seem to be consistently attenuated by controlling body mass index, menopausal status, or experience of hormone replacement therapy. CONCLUSION: The results from this meta-analysis suggest that sedentary behavior within the occupational domain was associated with a 15.5% increased risk of breast cancer. It is essential to reduce the sedentary time spent at work and to secure time for leisure-time physical activity among sedentary workers as a primary preventive measure.