Background: Arthroscopic rotator cuff repair (aRCR) has shown similar midterm functional results and retear rates as open/mini-open rotator cuff repair (oRCR). A pooled analysis of long-term results of both techniques is yet missing. Purpose: To evaluate the long-term results of aRCR and oRCR for full-thickness rotator cuff tears. Study Design: Systematic review; Level of evidence, 4. Methods: The systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The CENTRAL (Cochrane), MEDLINE (PubMed), and Embase databases were searched for studies that reported on long-term clinical and radiographic outcomes of full-thickness aRCR and oRCR with a minimum follow-up of 9 years. Results: Eleven studies were included: 5 studies on aRCR and 6 studies on oRCR. Studies were based on 550 shoulders (539 patients) with a mean patient age of 56.3 years (range, 25-77). After a mean follow-up of 14.0 years (range, 9-20), the mean preoperative absolute Constant score (CS) and American Shoulder and Elbow Surgeons (ASES) shoulder score were significantly improved postoperatively (CS, 44 to 78 points; ASES, 52% to 91%; both comparisons, P < .001). The retear rate was 41% (141 of 342 shoulders) without a significant difference between groups (aRCR, 43%; oRCR, 39%) (P = .364). A retear was associated with significantly reduced CS as compared with a healed repair (P = .004). No significant differences were found in postoperative functional scores, complications, and retear rates after failed cuff repairs between the arthroscopic and open/mini-open repair groups. Conclusion: Pooled analysis of arthroscopic and open rotator cuff repairs demonstrated sustained improvement in long-term shoulder scores and pain with a substantial retear rate in both groups, which was associated with inferior shoulder function. There were no significant differences in long-term functional outcomes, retear rates, and complications. Both surgical techniques may be used on the basis of factors such as patient or surgeon preference and cost. Further studies using a more robust randomized controlled trial or larger cohort design are recommended to ascertain whether one surgical repair technique is superior to the other. Registration: CRD42020180448 (PROSPERO).