1009 patients with open or closed extremity fractures treated with internal fixation were randomized to receive an online cognitive behavioural therapy (CBT) program with asynchronous therapist support or usual care. The primary outcome of interest was moderate-to-severe persistent post-surgical pain (PPSP), defined as a pain score of ≥4/10 on a visual analogue scale (VAS) over 12 months. Secondary outcomes included pain severity, physical functioning, mental functioning, pain interference, opioid use, return to work, return to household and leisure activities, and return to at least 80% of pre-injury functioning. Outcomes were assessed over 12 months following fracture fixation. Overall, the results of the study revealed no significant reduction in moderate-to-severe PPSP with online CBT compared with usual care. However, exploratory analyses suggested a potential benefit among patients with open fractures and in sites with higher treatment adherence. These findings suggest that routine online CBT does not reduce persistent post-surgical pain after fracture fixation, although specific higher-risk patient populations may derive benefit.