The limitation of tracking systems to assess short high intensity efforts has led to an exponential growth of inertial measurement units (IMU), capable of recording jumps at a very high sampling rate. However, the validity and reliability of each of them should be tested. This study aimed to assess the criterion validity and reliability of a new algorithm to detect jump performance in professional women’s volleyball players during training using an IMU. A total of 1581 jumps performed by 13 players (17.31 ± 7.34 years’ experience, and 6.77 ± 7 years playing in the first league) were video recorded during two volleyball training sessions. Data were recorded with Realtrack Systems IMU (WIMU PRO™, RealTrack Systems, Almeria, Spain), and extracted data were compared against a video system (Sony HDR-CX240 high-definition camera, Sony Corporation, Tokyo, Japan) using an observational procedure (ICC = 0.99). The results showed that WIMU PRO™ identified 1569 from the total of 1581 jumps performed (i.e. 99.24%). Therefore, this wearable device proved to have excellent jump count accuracy in top-level women’s volleyball players, making its use feasible in this sport context. This finding supports the use of this IMU as a valid method to guide the monitoring of jump training load.