Purpose: To compare functional outcomes and postural stability in patients undergoing primary anterior cruciate ligament (ACL) repair or hamstring tendon reconstruction, using healthy individuals as a reference. We hypothesized that primary ACL repair would result in superior subjective knee function and postural stability. Methods: This comparative case–control study assessed pain, function, single-leg hop performance and postural stability were assessed using the Visual Analogue Scale (VAS), Lysholm Knee Score, International Knee Documentation Committee (IKDC) Score and Biodex Biosway indices (OSI: overall stability index, API: anteroposterior index, MLI: mediolateral index) in bipedal and single-leg stance. Statistical analyses included one-way analysis of variance (ANOVA) or Kruskal–Wallis tests for group comparisons, with paired t-tests or Wilcoxon signed-rank tests for within-group comparisons, depending on data distribution. Results: A total of 113 participants were analyzed: primary repair (primary repair group [PRG], n = 40), reconstruction (reconstruction group [RG], n = 38), and control (control group [CG], n = 35) groups. Mean follow-up was 43.2 ± 10.1 months in PRG and 43.9 ± 11.7 months in RG. VAS scores were 1.37 ± 1.56 in PRG and 1.89 ± 1.62 in RG (mean difference [MD] = 0.51, 95% confidence interval [CI]: −0.19 to 1.23, p = 0.15). Lysholm scores were 92.6 ± 6.95 in PRG and 89.5 ± 9.09 in RG (MD = −3.02, 95% CI: −6.66 to 0.61, p = 0.10). IKDC scores were significantly higher in PRG (88.2 ± 9.01) than RG (82.6 ± 12.1) (MD = 5.63, 95% CI: 0.84 to 10.42, p = 0.02). On the operated side, MLI was lower in PRG (0.2 ± 0.3) than RG (0.3 ± 0.2) (MD = −0.05, 95% CI: 0.008 to 0.11, p = 0.02), indicating better mediolateral stability. Single-leg hop distance was shorter in RG (1.40 ± 0.28 m) and PRG (1.43 ± 0.27 m) compared with CG (1.62 ± 0.18 m) (CG vs. RG: MD = 0.22, 95% CI: 0.07 to 0.36; CG vs. PRG: MD = 0.18, 95% CI: 0.03 to 0.33; p = 0.001), despite LSI values exceeding 90% (RG: 93.1 ± 8.5%; PRG: 95.1 ± 6.3%). Conclusions: Primary anterior cruciate ligament repair provides comparable functional and postural outcomes to reconstruction and may offer superior subjective knee function and mediolateral balance in selected patients. Level of Evidence: Level III.