Between limb strength, asymmetry is a leading risk factor for hamstring strain re-injury. However, few accurate testing methodologies are available in clinical settings. This study examined the validity and reliability of eccentric knee flexor torque measured with a novel Nordic Hamstring Device. Twenty-seven healthy participants were assessed in two sessions. Maximal eccentric knee flexion torque was measured by the Biodex system 4 and during the Nordic Hamstrings Exercise in the FysioMeter. A moderate correlation was found between the FysioMeter and the Biodex (rho 0.674). Limits of agreement showed a bias of -43.9 Nm, suggesting that the FysioMeter underestimated the knee flexor peak torque compared with the Biodex. The FysioMeter showed excellent test-retest reliability (ICC 0.964). In conclusion, the FysioMeter provided moderately valid measures of knee flexor peak torque and excellent test-retest reliability. The FysioMeter could be a valuable tool for guiding rehabilitation in settings where access to isokinetic dynamometry is limited.