Aims Cardiac biomarkers are a mainstay in diagnosis of cardiovascular disease but their role in cardio-oncology has not yet been systematically evaluated. This meta-analysis aims to determine whether cardiac troponins and (N-terminal pro) brain natriuretic peptide (BNP/NT-proBNP) predict cancer therapy-related left ventricular (LV) dysfunction. Methods and results Scientific databases were searched for studies that assessed troponins or BNP/NT-proBNP in adult patients undergoing cancer therapy. Data from 61 trials with 5691 patients were included. Cancer therapy was associated with an increase in troponin levels [odds ratio (OR) 14.3, 95% confidence interval (CI) 6.0–34.1; n = 3049]. Patients with elevated troponins receiving chemotherapy or human epidermal growth factor receptor 2 inhibitor therapy were at higher risk for LV dysfunction (OR 11.9, 95% CI 4.4–32.1; n = 2163). Troponin had a negative predictive value of 93%. Mean BNP/NT-proBNP levels were increased in patients post-treatment (standardized mean difference 0.6, 95% CI 0.3–0.9; n = 912), but the available evidence did not consistently indicate prediction of LV dysfunction (OR 1.7, 95% CI 0.7–4.2; n = 197). β-blocker and angiotensin-converting enzyme inhibitor therapy to mitigate cardiotoxicity during cancer therapy was associated with a decline in serum troponins (OR 4.1, 95% CI 1.7–9.8; n = 466). Conclusion Elevated troponin levels predict LV dysfunction in patients receiving cancer therapy. Assessment of troponin levels may qualify as a screening test to identify patients who require referral to cardio-oncology units and benefit from preventive strategies. Further evidence is required for both biomarkers.