ObjectiveMetformin has attracted more attention from researchers for its newly discovered antitumor effects. A meta-analysis was performed to reveal the efficacy of metformin on overall survival (OS) and recurrence-free survival (RFS) for HCC patients with type 2 diabetes mellitus (T2DM) after curative treatment.MethodsDatabases including PubMed, the Cochrane Library, Web of Science, CNKI, Wangfang, and Weipu Database up until 31 May 2022 were searched for relevant studies. STATA 13.0 was used to perform the meta-analysis.ResultsA total of six studies involving 5,936 patients were included in our study. The results from the current study revealed that metformin usage can significantly prolong the 3-year [odds ratio (OR) = 1.50, 95% confidence interval (CI): 1.22–1.83, p = 0.000] and 5-year (OR = 1.88, 95% CI: 1.47–2.41, p = 0.000) OS and decrease the 1-year (OR = 1.31, 95% CI: 1.08–1.59, p = 0.007), 3-year (OR = 1.88, 95% CI: 1.48–2.37, p = 0.000), and 5-year (OR = 1.83, 95% CI: 1.40–2.40, p = 0.000) recurrence rates.ConclusionMetformin treatment significantly prolongs the OS and decreases the recurrence rate for HCC patients with T2DM after curative HCC therapy.