Hip flexors are critical in sprinting, with flexion angles exceeding 70–90° that stress the hamstrings. This study investigated whether a hip flexion exosuit (H-Fit, HUROTICS Inc.) could enhance sprint performance by increasing hip flexion angles and altering key biomechanical variables. One male participant performed treadmill sprints at 5, 6, and 7 m/s with and without the exosuit. A force treadmill collected ground reaction forces, while a motion capture system recorded movement at 300 Hz. Using IMUs to detect maximum hip extension (MHE) and flexion (MHF), the exosuit applied a sinusoidal force (peak 100 N) from MHE to MHF. With assistance, maximum hip flexion angle rose from 57.94° to 66.58° (+14.91%), 60.22° to 69.09° (+14.73%), and 62.09° to 67.31° (+8.41%) at 5, 6, and 7 m/s, respectively. At 7 m/s, peak vertical ground reaction force increased from 23.90 to 27.30 N/kg (+14.23%). Ground contact time dropped from 0.35 to 0.33 s (−5.71%) at 6 m/s and from 0.32 to 0.28 s (−12.50%) at 7 m/s. These findings suggest hip flexion assistance increases hip range of motion and may enhance sprint mechanics. Larger samples and individualized force profiles are needed to confirm and optimize these results