Maintenance of adequate blood perfusion and oxygen delivery is essential for cerebral metabolism. Cerebral oximeters based on near-infrared spectroscopy (NIRS) have been used for noninvasive, continuous, real-time monitoring of cerebral oxygen saturation and management of cerebral oxygen adequacy perioperatively and intraoperatively in various clinical situations, such as cardiac surgery, anesthesia, and cerebral auto-regulation. In this study, a portable and modular cerebral tissue oximeter (BRS-1) was designed for real-time detection of regional oxygen saturation over the brain, finger, or other targeted body tissues, as well as for wireless cerebral oxygenation monitoring. The compact and lightweight design of the system makes it easy to use during ambulance transport, in an emergency cart, or in an intensive care unit. The system performance of the BRS-1 oximeter was evaluated and compared with two US FDA-cleared cerebral oximeters during a controlled hypoxia experiment. The results showed that the BRS-1 oximeter can be used for real-time detection of cerebral desaturation with an accuracy similar to the two commercial oximeters. More importantly, the BRS-1 oximeter is capable of capturing cerebral oxygen saturation wirelessly. The BRS-1 cerebral oximeter can provide valuable insights for clinicians for real-time monitoring of cerebral/tissue perfusion and management of patients in prehospital and perioperative periods.