BACKGROUND: Triple-negative breast cancer constitutes approximately 12%-17% of all breast cancer cases, and >33% of patients develop distant metastases. Systemic cytotoxic chemotherapy is the primary treatment for patients with metastatic triple-negative breast cancer; however, the role of first-line platinum-based chemotherapy in these patients remains controversial. This meta-analysis evaluated the efficacy and safety of platinum-based first-line chemotherapy for patients with metastatic triple-negative breast cancer. METHODS: We systematically searched the PubMed, Embase, Cochrane, and Clinical Trials registry databases up to June 1, 2020 to identify randomized controlled trials that investigated platinum-based vs. first-line platinum-free chemotherapy in patients with metastatic triple-negative breast cancer. We used fixed and random effects models to calculate pooled hazard ratios and odds ratios with 95% confidence intervals for progression-free and overall survival, objective response rates, and grade 3 and 4 adverse events. RESULTS: Four randomized controlled trials (N = 590 patients) were included. Platinum-based chemotherapy significantly increased the objective response rates from 43.1% to 62.7% (odds ratio 2.34, 95% confidence interval 1.66-3.28, P < 0.001). Three randomized controlled trials (N = 414 patients) reported survival outcomes. Patients administered platinum-based regimens showed significantly longer progression-free survival (hazard ratio 0.55, 95% confidence interval 0.37-0.82, P = 0.004) and a nonsignificant trend toward improved overall survival (hazard ratio 0.76, 95% confidence interval 0.57-1.00, P = 0.05). Only 2 studies reported the rates of grade 3 and 4 adverse events; grade 3-4 thrombocytopenia was more commonly associated with platinum-based chemotherapy (odds ratio 7.54, 95% confidence interval 1.37-41.60, P = 0.02) and grade 3-4 fatigue with platinum-free chemotherapy (odds ratio 0.23, 95% confidence interval 0.08-0.68, P = 0.008). CONCLUSIONS: First-line platinum-based chemotherapy was associated with significantly increased objective response rates, longer progression-free survival, and a nonsignificant trend toward improved overall survival in patients with metastatic triple-negative breast cancer at the high risk of grade 3-4 thrombocytopenia.