We aimed to validate the Peak Velocity Method (PVM), independent of device-related errors, for measuring jump height and force-velocity profiles. Ten men (age: 20 ± 1 years, body height: 173.5 ± 4.7 cm, body mass: 76.2 ± 8.3 kg) performed two countermovement jumps under body mass (BM) and loaded conditions (BM + 32 kg and 1.6, 1.8, 2.0, and 2.2 BM). The jumps were analyzed using a force plate. Peak and take-off velocities were obtained from the same jump and substituted into the impulse-momentum method (IMM) equation to calculate jump height. The method using peak velocity was defined as the peak velocity method (PVM), while the method using take-off velocity was defined as the impulse-momentum method (IMM). The force-velocity profile variables were also derived using both methods. Compared with the IMM, the PVM consistently exhibited a positive fixed bias in jump height (0.036 ± 0.008 m) and force-velocity variables, with overestimation becoming more pronounced under loaded conditions (0.043–0.044 ± 0.009–0.010 m). Proportional bias was also evident in BM and force-velocity variables. Furthermore, force-velocity profile classification was affected by the PVM, misidentifying participants as transitioning from force deficit to velocity deficit. These findings indicate that, although widely adopted in inertial measurement devices due to its convenience, the PVM introduces measurable errors within the strict experimental conditions of this study and may be unsuitable for accurately assessing jump heights (Hedges’ g = 0.61–1.82) and force-velocity profiles (Hedges’ g = 1.00–10.81).