PurposeThe safety and reliability of endoscopic Achilles tendon rupture repair are still concerning aspects. This study's aim is to evaluate an all‐inside endoscopic semiautomatic running locked stitch (Endo‐SARLS) technique.MethodsForty cases with acute Achilles tendon rupture were treated with the all‐inside Endo‐SARLS technique between 2020 and 2021. Under endoscopic control, the proximal tendon stumps were stitched with the running locked method using a semiautomatic flexible suture passer. The threads of the high‐strength suture were grasped through the paratenon subspace and then fixed into calcaneal insertion with a knotless anchor. Magnetic resonance imaging (MRI), surgical time and complications were assessed. Achilles Tendon Total Rupture Score (ATRS), Achilles Tendon Resting Angle (ATRA) and Heel Rise Height Scale (HRHS) were utilised to evaluate final outcomes.ResultsThe average follow‐up time was 25.4 ± 0.4 (range: 24–32) months. Appropriate tendon regeneration was observed on MRI after 12 months. At the final follow‐up, the median value of ATRS score was 95 (interquartile range: 94, 98). Furthermore, there is no significant difference between the injured and contralateral side in the average ATRA (18.2 ± 1.8 vs. 18.3 ± 1.9°, ns) and median value of HRHS [14.5 (13.3, 15.5) vs. 14.8 (13.5, 15.6) cm, ns]. No infection and nerve injuries were encountered. Thirty‐nine patients reported that they resumed casual sports activity after 6 months. One patient had a slight anchor cut‐out, due to an addition injury, which was removed after 5 months.ConclusionsAn all‐inside Endo‐SARLS technique showed promising clinical results for acute Achilles tendon ruptures. This procedure reduces the risk of sural nerve injuries while establishing a reliable connection between the tendon stumps.Level of EvidenceLevel IV.