This study investigated the effects of ankle bracing on proprioception, agility, and lower-extremity biomechanics in 12 professional male basketball players. Ankle proprioception was assessed using the joint position reproduction (JPR) test, and kinematic data were captured using a 3D wearable motion capture system (Xsens MVN Awinda) during the change of direction (COD) agility T-Test. Tests were performed under braced and non-braced conditions (W bracing and WO bracing conditions, respectively). No statistically significant differences were found in proprioceptive accuracy between conditions (p = 0.975 and p = 0.995 for performed vs. reference angle errors in WO bracing and W bracing conditions, respectively). Similarly, no significant differences were observed in average velocity or time during COD movements (p > 0.05). However, the brace significantly restricted ankle range of motion, with the absolute angular error (AAE) in internal/external rotation reaching 3.03. Knee kinematics showed increased flexion restriction (AAE = 4.86) and moderate changes in abduction/adduction (AAE = 1.36). At the hip, internal rotation increased under the braced condition, though differences were not statistically significant (AAE = 2.80). Despite these biomechanical alterations and a non-significant reduction in proprioceptive feedback, agility performance was maintained (p > 0.05). These results suggest that while ankle bracing alters joint kinematics and limits ROM—especially at the ankle and knee—it does not significantly compromise agility performance. Prolonged use, however, may increase reliance on external stabilization, emphasizing the need for concurrent proprioceptive training in injury prevention protocols.