Purpose: The purpose of this study was to evaluate the radiographic and clinical outcomes of hook plate fixation with and without coracoclavicular (CC) ligament augmentation with suture anchors for acute acromioclavicular (AC) joint dislocation. Methods: The study included 67 patients (48 males and 19 females; average age: 45.5 years) with acute AC joint dislocation (Rockwood types III and V) treated with hook plate fixation. The patients were divided into two groups: those treated with hook plate fixation with or without CC ligament augmentation with suture anchors. We used the CC distance and ratio as radiographic outcomes. We evaluated the American Shoulder and Elbow Surgeons (ASES) score and the Constant Shoulder Score as functional outcomes. The following were considered major complications: symptomatic acromial osteolysis, peri‑implant fracture, acromial cut‑out, and hook plate disengagement. Results: Among the Rockwood type III patients, there was no significant difference between the two subgroups in terms of the functional outcome after adjusting for sex and age. However, among the type V patients, treatment with CC ligament augmentation with suture anchors revealed a superior outcome in terms of the ASES score (P = 0.01). There was no difference in the risk of developing major complications between the two subgroups among type III and type V patients. The risk of residual subluxation of the AC joint was significantly lower in the CC augmentation subgroup among the type III patients (P = 0.04), and a similar result was obtained among the type V patients with borderline significance (P = 0.06). Conclusions: Hook plate fixation with CC suture anchor augmentation provided radiographic benefits in both type III and type V patients and yielded better functional outcomes in type V patients after implant removal but had no significant influence on the complication rate. Additional CC suture anchor augmentation may prevent residual subluxation and yield better functional outcomes.