Background: Clinically significant outcome (CSO) thresholds for the Patient-Reported Outcome Measurement Information System–Upper Extremity (PROMIS–UE) score have been previously defined after arthroscopic rotator cuff repair (RCR). However, the time required to achieve CSOs for the PROMIS–UE score is unknown. Purpose: To (1) determine the time required to achieve the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and Patient Acceptable Symptom State (PASS) score thresholds after RCR for the PROMIS–UE questionnaire and (2) identify patient factors associated with earlier or delayed achievement of these clinical benchmarks. Study Design: Case-control study; Level of evidence, 3. Methods: A prospectively maintained institutional database was retrospectively reviewed for consecutive patients who underwent RCR between January 2018 and January 2019. Patients were included if they completed the PROMIS–UE questionnaire both preoperatively and at standardized postoperative time intervals: 5 to 7 months (6-month time point), 11 to 13 months (1-year time point), and ≥23 months (2-year time point). Kaplan-Meier survival curves with interval censoring were used to define the cumulative percentage of patients who achieved the MCID, SCB, and PASS. Patient variables associated with earlier or delayed achievement of the MCID, SCB, and PASS were determined using Weibull parametric survival regression analysis. Results: Included were 105 patients undergoing RCR (age, 57.3 ± 10.3 years; body mass index, 31.5 ± 6.1 kg/m2). By 2-year follow-up, the cumulative percentage of patients achieving the MCID, SCB, and PASS was 86.7%, 76.2%, and 74.3%, respectively. The mean time required to reach the MCID, SCB, and PASS score thresholds was 9.5 ± 3.8, 10.3 ± 4.4, and 9.8 ± 4.6 months, respectively. Factors associated with delayed achievement of CSOs included greater baseline PROMIS–UE score (MCID and SCB) and workers’ compensation insurance (PASS). Greater baseline PROMIS–UE scores were associated with earlier achievement of the PASS. Conclusion: Most patients achieved CSOs for the PROMIS–UE within 12 months of RCR. Patient-specific factors found to be associated with earlier or delayed achievement of CSOs can be used to inform patient discussions on the expected timeline for recovery after RCR.