INTRODUCTION AND IMPORTANCE: Ulnar collateral ligament (UCL) injuries of the thumb's metacarpophalangeal (MCP) joint are commonly seen in athletes and result from forced abduction or hyperextension of the thumb. CASE PRESENTATION: This case involved a 29-year-old female who presented with simultaneous pain and instability in both thumbs after a traumatic incident. Bilateral ulnar collateral ligament (UCL) rupture was confirmed radiographically. Open repairs were performed using the pull-out technique and cast spica, followed by postoperative rehabilitation. CLINICAL DISCUSSION: The patient demonstrated full recovery of thumb mobility, strength, and stability within six months post-surgery. CONCLUSION: This case report presents a rare instance of acute bilateral UCL rupture due to direct trauma. Early diagnosis and prompt surgical intervention led to the successful restoration of thumb stability and function. This case emphasizes the importance of surgical repair in cases of displaced UCL injury to prevent long-term instability and loss of thumb function.