Telemonitoring of biosignals is a growing area of research due to the aging world population. Telemonitoring utilizes a wireless body-area network (WBAN) consisting of wearable biosignal sensors equipped with ultra low power radios. The measured data from each sensor on the patient is sent to a smartphone, which then sends the data to a healthcare provider via the internet. To enable real-time telemonitoring of the biosignals, it is desirable to have accurate timestamped data from the sensors in the WBAN. This is especially important for data consistency to sensors that store their measured data and infrequently send it to the smartphone. This letter presents a novel synchronization algorithm that exploits the R peaks of the electrocardiogram (ECG) data that is transmitted to the smartphone. To the best of the author’s knowledge, this is the first time the R peak has been used as a signal of opportunity (i.e., any signal that is used for positioning, navigation, or timing (PNT), even though the signal is not originally intended for PNT applications) for synchronization. The R peaks serve as the reference broadcast for the WBAN in a reference-broadcast synchronization (RBS) scheme. Simulation results using low cost sensors and an actual 24 hour ECG recording show that the smartphone can determine the timing of the WBAN sensor data accurately at any time within the 24 hour period to within ~30μs. Without synchronization, the sensor data would have a timing offset of 8 seconds by the end of the 24 hours.