Abstract Background: This study aimed to assess the clinical result, complications, failure rate, and return to resuming military duty of a single-stage anterior cruciate ligament reconstruction (ACLR) procedure utilizing quadrupled semitendinosus tendon graft joint with modified lateral extra-articular tenodesis (LET). This study evaluates the potential impact of combined modified LET with ACLR versus ACLR alone on the rate of return to high-impact military activities, which we call return to sports (RTSs), and the subsequent rate of the anterior cruciate ligament (ACL) graft failure. Materials and Methods: A total of 198 soldiers with primary ACL tears with a high-grade pivot test (grade 3) were included and randomized using the simple randomized method and divided into two groups. A consecutive cohort of military personnel with an isolated ACL tear undergoing ACLR with modified LET (group A, n = 116) and ACLR alone (group B, n = 82) were analyzed between 2016 and 2021. Both groups were followed up for a minimum of 2 years. Soldiers underwent a survey evaluating knee function (knee injury and osteoarthritis outcome score [KOOS]), RTS criteria (RTS type), symptoms (International Knee Documentation Committee [IKDC] subjective), activity level (Tegner score), and fear of movement (Tampa Scale of Kinesiophobia-11) to assess psychological readiness for sport participation. Results: Among these, a mean age of 32 ± 2.93 years underwent primary ACLR with modified LET (n = 116) or without LET (n = 82) procedure. A total of 31 soldiers (15.6%) experienced ACL graft failure, including 26 (31.7%) reconstructions without LET and 5 (4.3%) with LET. Combined with LET during primary ACLR, it lowered the risk of graft failure by 2.8 times. Multivariable analysis revealed a significant reduction in graft rupture risk (relative risk = 0.325, P = 0.029) associated with LET compared to ACLR alone after adjusting for age, anthropometric factors, and tibial slopes. 105 out of 113 (90.5%) soldiers were able to return to military duty in group A (combined ACLR with modified LET), whereas 51 of 81 (62.9%) of the soldiers who underwent ACLR alone (group B) returned to military duty (P = 0.05). Conclusion: At 24 months postoperatively, combined ACLR plus LET showed a significantly higher RTS rate than ACLR alone. The combined ACLR with the modified LET group also showed a lower failure rate than the ACLR alone group. No marked differences were observed in KOOS sub-scores, IKDCsubjective, and Tegner activity scores.