Capsular closure in femoroacetabular impingement syndrome (FAIS) patients during hip arthroscopy procedures is debated. The Danish Hip Arthroscopy Registry (DHAR) contains data to perform matched-cohort analyses. The purpose of this study is to evaluate 1-year subjective outcome data from DHAR after hip arthroscopy for FAIS with capsular closure and compare these outcome data with a matched-cohort study group. The primary hypothesis was that there would be no difference in Copenhagen Hip and Groin Outcome Score (HAGOS) subjective outcome between patients with and without capsular closure. This is a retrospective cohort study (level of evidence, 3). FAIS patients eligible for hip arthroscopy between January 2012 and December 2017, and where the interportal capsulotomy was closed, were identified and matched with patients without capsular closure. Matching criteria were gender (1:1), age (+/- 5 years), degree of cartilage injury: ICRS and modified Becks grade (+/- 1 grade) and radiological parameters: lateral center edge angle and alpha angle (+/- 10 degrees). A comparison between cohorts regarding differences in patient outcome scores, HAGOS, Hip Sports Activity Scale (HSAS), EuroQol-5 Domain (EQSD) and numeric rating scale (NRS) pain at 1-year follow-up were performed. Wilcoxon rank-sum test was used to compare differences between preoperative and postoperative subjective outcome scores, level of statistical significance was 0.05. A total of 189 patients were included in the capsular closure group and matched with 189 control patients. The mean age in years (+/- standard deviation) was 39.4 (+/- 11.8) and 39.3 (+/- 11.2), respectively, 55% females. Both groups improved significantly at 1-year follow-up. Significant improvements in the capsular closure group were found in HSAS, EQSD, NRS pain (rest and walk) and most HAGOS subscales compared with the non-closure group. All patients underwent labral repair in combination with both femoral osteochondroplasty and acetabuloplasty. The revision rate reported after 2 years was 6.8% in the non-closure group and 3.5% in the closure group. One patient in each cohort received a total hip replacement after 2 years. Capsular closure during arthroscopic FAIS treatment resulted in better subjective outcomes and less pain during rest and walking compared with matched controls. Both groups demonstrated improved outcome at 1-year follow-up. Furthermore, capsular closure might result in a lower risk of a revision hip arthroscopy.