Background: This systematic review and meta-analysis assessed the data from cohort studies that compared treatment with or without incretins and the incidence of breast cancer (BC) due to the current controversies. Methods: PubMed, Scopus, EMBASE, Cochrane, ProQuest, Ovid, and Google Scholar were searched for relevant studies. A secondary analysis was conducted to compare the effect of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 inhibitors (DPP-4Is) on BC development. Results: The meta-analysis of four studies with 58,767 patients and 461,475 controls revealed that incretin-based therapies increase the incidence of BC insignificantly (risk ratio (RR)=1.23, 95% confidence interval (CI)=0.44–3.40; P=0.69). The DPP-4I group significantly reduced the risk of BC compared to the GLP-1RA group (RR=0.43, 95% CI=0.32–0.59; P<0.00001). Conclusion: This study found no evidence of a substantial increase in BC incidence in patients with type 2 diabetes taking GLP-1RAs and DPP-4Is. However, DPP-4Is were less likely than GLP-1RAs to cause BC formation.