This study aims to evaluate the return to sport and correlations of patients with symptomatic borderline hip dysplasia (BHD) after hip arthroscopy and T-shaped capsular plication at a minimum follow-up of 24months. Twenty-five patients who underwent hip arthroscopy and T-shaped capsular plication for symptomatic BHD were included in the study. All the patients were evaluated clinically prior to surgery (T0) and at two consecutive follow-ups (T1:15 ± 1.2months and T2: 53.9 ± 23.2months) using the visual analogue scale (VAS) pain score, whereas sports activity was assessed by the Hip Outcome Score Sport Specific Subscale (HOS-SSS), the University of California, Los Angeles (UCLA) activity scale, the Tegner score and the physical component (PCS) of the Short Form-12 (SF-12). Furthermore, the presence of correlations and the possible differences between subgroups were evaluated and analysed. A significant difference was found for HOS-SSS, VAS, Tegner, UCLA and PCS with the Friedman test for repeated measures through time points (p < 0.0001). Moreover, all the scores reported significant improvement compared to the previous time point (p < 0.0001) except the HOS-SSS between T1 and T2 (n.s.). Body Mass Index (BMI) was negatively correlated with HOS-SSS at T0 (rho = -0.526 p = 0.006) and T1 (rho = -0.425; p = 0.034), with Tegner at each follow-up (T0: rho = -0470 p = 0.017; T1: rho = -0.450; p = 0.024; T2: rho = -0.448; p = 0.024), with UCLA at T1 (rho = -0.396 p = 0.049), with pre-operative PCS (rho = -0.413 p = 0.0401), and positively correlated with pre-operative VAS (rho = 0.436 p = 0.0291). Hip arthroscopy and T-shaped capsular plication in young patients with symptomatic BHD demonstrates a significant increase in return to sport and physical activity and low risk of complications. T-shaped capsular plication procedure may be considered in young and active patients for whom non-operative treatment failed and who have a significant limitation in sports activity; in these patterns of patients, the ideal treatment should reliably allow fast recovery in combination with very low invasiveness which will prevent osteoarthritis. The results of this study provide more accurate information regarding return to sport in patients with BHD after hip arthroscopy and T-shaped capsular plication. Level IV.