Background: Acute ankle injuries are common in sports and daily activities. Kinesiology taping enhances lower limb motion patterns, joint stability, and balance during descending stair activity in such patients. The objective of this study was to conduct a comparative analysis of the biomechanical impacts exerted by a KT group and an ST group on the lower limbs of patients with acute ankle injuries while descending stairs. Methods: The study included 27 participants with acute ankle injuries, who underwent biomechanical assessment under both KT and ST conditions. An integrated Vicon motion capture system, AMTI force platform, and electromyography (EMG) sensors were utilized to comprehensively evaluate biomechanical performance. Participants completed 20 descending stair trials under each condition, with joint stiffness, center of mass (COM), and bone displacement identified as key metrics for assessing stability. Statistical analyses, including paired t-tests and statistical parametric mapping (SPM1D), were employed to identify significant biomechanical differences between the two conditions. Results: The study revealed that compared to ST, kinesiology taping significantly reduced inversion and eversion angles (p < 0.001). Electromyography (EMG) analysis of the KT group revealed a remarkable enhancement in the activation levels of the calf muscle group (p < 0.001). In stark contrast to the ST group, the KT group demonstrated a substantial increase in ankle joint stiffness. Moreover, the KT group also achieved elevation in the activation of the hip muscles, with all these differences being highly significant (p < 0.001). Conclusion: Research shows that individuals with acute ankle joint injuries face issues such as significant inversion and eversion angles, reduced ankle joint stiffness, and persistent joint instability when descending stairs. Kinesiology taping can address these issues by reducing joint angles, increasing stiffness, and balancing moments. KT also stabilizes the center of mass and diminishes fall risks. This demonstrates that kinesiology taping effectively enhances stability during descending stairs and helps prevent recurrent injures. It is recommended as a protective measure following acute ankle injuries. Trial registration: ClinicalTrials.gov NCT06936033, registered on April 19, 2025 (Retrospectively registered).