Objectives: To evaluate the effect of topical corticosteroids (TCS) in preventing acute radiation dermatitis in patients with breast cancer. Methods: An updated systematic review and meta-analysis were conducted following the preferred reporting items for systematic reviews and meta-analyses. Randomized controlled trials (RCTs) in six English databases (PubMed, Web of Science, Scopus, CINAHL, Cochrane Library, Embase), three Chinese databases (Sinomed, China National Knowledge Infrastructure, Cqvip), and two clinical trial registration platforms (CHICTR, Clinicaltrials.gov) were systematically searched from inception to 1 February 2024. Results: Thirteen RCTs were included, with 1172 patients in this updated review. Meta-analysis showed that TCS reduced the rate of moist desquamation (OR = 0.31; 95% CI = [0.22, 0.44]; P < 0.01), the incidence of Radiation Therapy Oncology Group ratings of grade 2 or higher (OR = 0.22; 95% CI = [0.14, 0.32]; P < 0.01), the incidence of Common Terminology Criteria for Adverse Events ratings of grade 2 or higher (OR = 0.56; 95% CI = [0.37, 0.84]; P < 0.01), the mean score of radiation dermatitis (SMD = -0.46; 95% CI = [-0.59, -0.34]; P < 0.01), skin erythema and hyperpigmentation readings, and improved subjective symptoms. Conclusions: TCS can effectively prevent acute radiation dermatitis in patients with breast cancer. Systematic review registration: Prospero (CRD42024507890).