Background The interosseous talocalcaneal ligament (ITCL) is the primary restraint of the subtalar joint. Injury to the ITCL results in subtalar instability. A novel ITCL augmentation repair technique has been developed as a potential minimally invasive surgical treatment option for ITCL injury. Surgical Technique Under endoscopic guidance, a calcaneal tunnel is created at just lateral to the anatomic ITCL insertion through an upper sinus portal. A high-strength, nonabsorbable suture tape is secured to this tunnel with the use of a tap-in–type suture anchor. From a small dorsal incision accessing the dorsomedial talar neck, a talar tunnel toward the proximal ITCL insertion at the deep part of the sinus is created with the use of a targeting device. The tape is pulled out dorsally through the talar tunnel and is secured with the use of an interference screw. Outcomes Immediate symptom reduction was reported in five preliminary patients who underwent the procedure, including two adult women and three young, female athletes. Conclusion The ITCL augmentation repair technique has potential as an adjunct procedure to decrease the risk of subtalar instability after scar tissue débridement in patients with sinus tarsi syndrome and as a minimally invasive surgical treatment option to restore hindfoot stability in athletes with subtalar instability.