Obesity and type 2 diabetes are major risk factors for cardiovascular diseases and multiple malignancies, and epidemiology reveals an increasing burden of obesity-related cancers, in particular liver, pancreatic and endometrial. Obesity is also clearly associated with an increased risk of breast cancer, particularly in postmenopausal women. Chronic hyperinsulinemia, systemic inflammation, and metabolic dysregulation create a tumor-promoting environment, emphasizing the need for interventions that target metabolic health and can provide cancer prevention or interception. This review examines the potential cancer-preventive effects of antidiabetic and anti-obesity drugs, summarizing current preclinical and clinical evidence on their mechanisms and efficacy. Among these agents, metformin has been extensively studied, demonstrating anticancer properties through AMP-activated protein kinase activation, mammalian target of rapamycin inhibition, and reduced insulin-like growth factor 1 signaling. Glucagon-like peptide-1 receptor agonists, including semaglutide and tirzepatide, promote weight loss, insulin sensitivity, and anti-inflammatory effects, with emerging evidence suggesting direct tumor-suppressive actions. Sodium-glucose cotransporter 2 inhibitors modulate tumor metabolism by reducing glucose availability and mitigating systemic inflammation. Other agents, including dipeptidyl peptidase-4 inhibitors, thiazolidinediones, sulfonylureas, and alpha-glucosidase inhibitors, have shown mixed evidence regarding their potential anticancer effects, necessitating further investigation. While observational studies and meta-analyses suggest a potential reduction in cancer risk with certain antidiabetic and anti-obesity agents, randomized controlled trials specifically assessing cancer prevention are limited. Additionally, long-term safety concerns, including potential tumor-promoting effects in specific contexts, warrant further investigation. Future research should focus on large-scale clinical trials and mechanistic studies to validate the oncologic benefits and risks of these agents.