Background: Surgical outcomes for proximal hamstring avulsion injury (PHAI) are well documented, yet comparative analyses with nonsurgical approaches remain scarce. Purpose: To compare the functional outcomes between surgical and nonsurgical interventions for PHAI. Study Design: Cohort study; Level of evidence, 3. Methods: This comparative study, conducted at a sports surgery center between January 2012 and July 2021, focused on patients with primary PHAI. The study was a retrospective analysis of prospectively collected data. Group selection involved utilizing propensity score matching to compare an arm of patients who were surgically treated (indications included patients with complete injury, patients with partial injury with >2 cm of retraction, and patients for whom 6 months of nonsurgical treatment failed) with another arm of patients who refused surgery. The primary outcome was evaluated using the Parisian Hamstring Avulsion Score (PHAS). The secondary outcomes included the Tegner Activity Scale (TAS) score; University of California, Los Angeles (UCLA) score; rate and quality of return to sport (RTS); and patient satisfaction. Results: The study included 32 patients (mean age, 55.8 years [SD, 8.4 years]) in the nonsurgical treatment arm and 95 patients in the surgical treatment arm (mean age, 53.4 years [SD, 7.7 years]) (P > .05). The interval from injury to treatment was 5.7 months (SD, 9.6 months) for the surgical group and 12.7 months (SD, 25.9 months) for the nonsurgical group (P > .05). At the final follow-up (nonsurgical group: mean, 56.5 months [SD, 28.2 months]; surgical group: mean, 50.7 months [SD, 33.1 months]), the PHAS was significantly higher in the surgical group (mean, 86.3 [SD, 13.7]) compared with the nonsurgical group (mean, 69.8 [SD, 15.1]) (P < .0001). Higher activity scores were also observed in the surgical group for the TAS and UCLA scores (P = .0224 and P = .0026, respectively). A higher percentage of the surgical group (68.4%) returned to sports compared with the nonsurgical group (46.9%) (P = .0354), with a greater proportion in the surgical group returning at the same or higher level (67.7% vs 26.7%) (P = .0069). Additionally, a higher satisfaction level was reported by patients in the surgical group (89.5%) in contrast to the nonsurgical group (25%) (P < .0001). Three patients in the surgical group experienced complications (2 reruptures and 1 hyperesthesia at the pudendal nerve territories). Odds ratios (ORs) indicated that patients in the surgical group were significantly more likely to achieve or exceed median scores for the PHAS (OR, 6.79; P < .001), TAS score (OR, 2.29; P = .045), and UCLA score (OR, 3.63; P = .003), as well as to RTS at any level (OR, 2.46; P = .031) or at the preinjury level or higher (OR, 6.04; P < .001). Conclusion: This study demonstrated that surgical treatment of PHAI significantly enhances long-term functional scores, including the PHAS, TAS score, UCLA score, satisfaction, and RTS, at a mean follow-up of >4 years compared with nonsurgical treatment. Registration: NCT02906865 (ClinicalTrials.gov identifier)