BACKGROUND: Chronic ankle instability (CAI) is a common injury among athletes. Research has reported reduced dorsiflexion range of motion, impairment of proprioception, and decreased muscle strength of the ankle in people with CAI. The aim of this research was to examine the effects of 8-week core stability training on stable and unstable surfaces on ankle muscular strength, proprioception, and dorsiflexion range of motion (ROM) in athletes with CAI. METHODS: Thirty-six athletes with CAI (age 22.42 ± 2.76 years; height 169.11 ± 3.52 cm; weight 68.46 ± 2.75 kg) participated in this study. They were divided into three groups: unstable-surface group (UG) (n = 12), stable-surface group (SG) (n = 12), and control group (CG) (n = 12). The UG and SG performed the core stability exercise protocol for 8 weeks, 3 sessions per week. The CG received their usual care and daily activities. Outcomes were measured pre-sessions and post-sessions. RESULTS: The peak torque showed significant increases in the UG and SG compared with the CG during plantar flexion, dorsiflexion, inversion, and eversion (P < 0.05). There were also significant increases in UG compared with SG (P < 0.05). The proprioception showed significant decreases in UG compared with SG and CG (P < 0.05). The dorsiflexion ROM showed significant increases in UG and SG compared with CG. There were also significant increases in UG compared with SG (P < 0.05). CONCLUSIONS: It seems that core stability exercises on trampoline surface helps improve the measured parameters in athletes with ankle instability. Therefore, this type of training is recommended as a therapeutic option for Individuals with CAI.