Objective To compare the impact of different peroneus longus tendon (PLT) stump management techniques on ankle function following arthroscopic anterior cruciate ligament (ACL) reconstruction with autologous PLT grafts. Methods A retrospective analysis was conducted on 60 patients with ACL rupture who met the inclusion criteria between August 2020 and July 2024. All patients underwent arthroscopic ACL reconstruction using the autologous PLT grafts. Patients were assigned to group A [PLT stump sutured to peroneus brevis tendon (PBT), n=30] or group B (no stump intervention, n=30). The two groups showed no significant difference (P>0.05) in baseline data, including gender, age, body mass index, injury mechanism, affected side, preoperative American Orthopaedic Foot and Ankle Society (AOFAS) score, ankle muscle strength, ankle range of motion, and arch-related angles. Postoperative outcomes were assessed using the AOFAS score, ankle muscle strength (eversion and first-ray plantar flexion), arch-related angles (medial/lateral longitudinal and anterior/posterior arch), ankle range of motion (eversion, inversion, dorsiflexion, plantarflexion), and limb symmetry index (LSI). Change values in muscle strength, arch-related angles, and range of motion from preoperative to 12 months postoperatively were calculated for intergroup comparison. Results Groups A and B had comparable PLT graft lengths and diameters (P>0.05). All patients were followed up 13-16 months (mean, 14.5 months). Postoperative complications included 1 case of incision infection, 1 case of deep vein thrombosis, and 1 case of knee stiffness in group A, 1 case of knee stiffness in group B. There was no significant difference in the overall complication incidences between groups (P>0.05). No significant difference was found in the AOFAS scores between different time points and between groups (P>0.05). At 12 months after operation, neither group showed significant changes from preoperative baseline in ankle strength, range of motion, or arch-related angles, and there was no significant difference in these change values between groups (P>0.05). There was no significant difference in LSI between the two groups at 6 or 12 months postoperatively (P>0.05). Conclusion Both suturing and leaving the PLT stump untreated during arthroscopic ACL reconstruction provided comparable ankle outcomes and well-preserved foot and ankle function.