Background: Mental health influences postoperative outcomes in orthopedic procedures. Increasing attention is being paid to this effect. Purpose: We sought to evaluate the effect of diagnosed depression, anxiety, or both on postoperative outcomes in patients who have undergone hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Methods: We conducted a retrospective cohort study of 289 patients aged 30 years or younger who underwent hip arthroscopy for FAIS at a single institution from January 2014 to June 2021. Univariate statistics were used to assess differences between patients diagnosed with depression, anxiety, or both, and those without these diagnoses. Differences included demographics, operative characteristics, and postoperative outcomes: duration of postanesthesia care unit (PACU) stay, PACU pain scores, complications, reoperations, postoperative injections, 90-day emergency department (ED) visits, and patient-reported outcome measures (PROMs). Multivariate analysis was used to evaluate risk factors for postoperative complications, including wound infection, documented reinjury, postoperative intra-articular hip injection, and any reoperation. Results: Patients diagnosed with depression, anxiety, or both were more likely to be older, female, and have a higher comorbidity burden. At the time of surgery, they were more likely to undergo concomitant procedures, including bursectomy and iliotibial band release. Postoperatively, they had longer PACU stays (90.5 vs 75.1 minutes) and higher first PACU pain scores (5.9 vs 4.6), as well as higher rates of postoperative injection (18.1 vs 9.2%), any reoperation (13.9% vs 4.6%), and revision hip arthroscopy (11.1% vs. 3.7%). Diagnoses of depression, anxiety, or both were independently predictive of any reoperation (odds ratio [OR] = 2.841) and revision hip arthroscopy (OR = 3.401). Conclusion: This retrospective cohort study found that, in patients undergoing hip arthroscopy for FAIS, there was an association between a diagnosis of depression, anxiety, or both, and increased comorbidities, higher first PACU pain scores, longer PACU stays, and increased rates of postoperative injection, any reoperation, or revision hip arthroscopy. Targeted interventions may improve outcomes, but further study is warranted.