Purpose <p>This proof-of-concept study examines the immediate biomechanical effects of a trunk angle-controlled vibrotactile feedback system on gait kinematics and symmetry in a lower limb amputee.</p> Methods <p>A wearable system incorporating a single inertial measurement unit (IMU) and a vibrotactile motor was developed to provide discrete, constant-magnitude vibrotactile feedback triggered only when trunk angles exceed predefined threshold. A 24-year-old female with left knee disarticulation participated in a single 80-minute gait training session using the system. Pre- and post-training gait analyses were conducted using a motion capture system to assess spatiotemporal parameters, symmetry indices, lower-limb kinematics in sagittal plane, and trunk motion.</p> Results <p>Post-training observations indicated increases in stride length (+ 8.94% on the prosthetic side), gait velocity (+ 15.31%), and cadence (+ 6.14%). Symmetry indices for stride length and double support shifted toward more symmetrical ranges. Prosthetic knee flexion during swing increased (16.47° to 34.13°), while trunk obliquity decreased (5.03° to 4.3°). These changes were observed within a single training session.</p> Conclusion <p>A single session employing trunk angle–based vibrotactile feedback was associated with short-term observable changes in gait kinematics and symmetry. Due to the single-subject design, findings should be interpreted as preliminary. Further studies with larger samples and controlled designs are required.</p>