Intraoperative transesophageal echocardiography (IO-TEE) is an indispensable tool in cardiac surgery, providing real-time imaging and hemodynamic assessment to guide surgical decision-making and optimize patient outcomes. This review highlights the critical role of IO-TEE in evaluating cardiac structures, valvular function, and hemodynamics, particularly in complex procedures such as valve repair or replacement, congenital heart surgery, and mechanical circulatory support (MCS) device implantation. IO-TEE aids in the detection of surgical complications, assessment of ventricular function, and management of hemodynamic instability, making it a cornerstone of intraoperative care. Key applications of IO-TEE include the assessment of mitral, aortic, and tricuspid valve pathologies, evaluation of left and right ventricular function, and guidance during MCS placement, including left ventricular assist devices (LVADs) and extracorporeal membrane oxygenation (ECMO). IO-TEE is also instrumental in identifying intracardiac shunts, thrombi, and air emboli, ensuring proper cannula positioning, and monitoring postimplantation device function. Furthermore, IO-TEE plays a pivotal role in high-risk noncardiac surgeries, where unexplained hemodynamic instability necessitates rapid diagnostic intervention. Despite its safety profile, IO-TEE is not without risks, with potential complications including gastrointestinal injuries and dysrhythmias. Careful patient selection, proper technique, and adherence to established guidelines are essential to minimize risks. This review underscores the importance of a comprehensive IO-TEE examination, utilizing both 2D and 3D imaging, to provide detailed anatomical and functional insights. By integrating IO-TEE findings into surgical planning and intraoperative management, clinicians can enhance procedural success and improve patient outcomes in cardiac surgery and beyond.