This study aimed to identify the optimal timing for starting mobilization after enthesis repair surgery. A total of 28 8-week-old male Wistar rats underwent bilateral Achilles tendon detachment and repair. We randomized animals into four groups based on the duration of immobilization:​ no cast group, no immobilization;​ 7 days group, immobilization for 7 days;​ 14 days group, immobilization for 14 days;​ or 30 days group, immobilization for 30 days. Samples were harvested for biomechanical and histological analyses following euthanasia at 30 days after surgery. Histological findings showed abundant fibrocartilage formation in 7 days group, limited fibrocartilage formation in 14 days group, and no fibrocartilage formation in no cast or 30 days group. Histological score was significantly higher in 7 days group than in no cast and 30 days groups (p < 0.05 each). Biomechanical analysis showed that the mean load to failure was significantly higher in 7 days and 14 days groups than in no cast and 30 days groups (p < 0.05). These findings suggest that starting mobilization following short-term (1 week) immobilization is the optimal timing to improve structural and mechanical properties of healing enthesis. This provides insight into the optimization of rehabilitation protocols following enthesis repair surgery.