Cardiotoxicity is one of the major side effects of anti-cancer therapy affecting the overall prognosis of patients and possibly leading to the discontinuation of chemotherapy. Traditional cardiovascular tests such as electrocardiography and transthoracic echocardiography have limited sensitivity and specificity for the early detection of myocardial injury. Cardiovascular imaging generally detects cancer therapy-related cardiac dysfunction (CTRCD) at advanced stages, whereas biomarkers are inexpensive, easily detected, reproducible, and capable of detecting even minimal cardiomyocyte damage or mild hemodynamic fluctuations. The presence of circulating cardiac biomarkers has been investigated as early indicators of cardiotoxicity and predictors of subsequent CTRCD. Currently, the most frequently used cardiac biomarkers are cardiac troponin (cTn) and natriuretic peptides (NPs). This review presents the evidence gathered so far regarding the usefulness and limitations of cardiac biomarkers in the field of cardio-oncology.