Irreparable large to massive rotator cuff tears (MIRCTs) are a prevalent cause of shoulder pain and dysfunction, and nonoperative treatment may not always be effective. Various surgical options exist, with isolated biceps tenotomy/tenodesis (BT) or arthroscopic partial repair with associated biceps tenotomy/tenodesis (PCR-BT) being the most common. The aim of this study was to systematically review the available data on the clinical and functional outcomes of BT and PCR-BT in patients with MIRCTs. Methods: MEDLINE, Embase, and CENTRAL databases were searched for studies on the treatment of MIRCT. We included studies with BT or PCR-BT with a minimum follow-up of 24 months. The MINORS (Methodological Index for Nonrandomized Studies) score was used to assess study quality. Outcomes included were the visual analog scale for pain, functional scores such as Constant-Murley and American Shoulder and Elbow Surgeons, range of motion, radiological measurements, and complications. Results: A total of 1101 patients (506 had a BT and 595 had a PCR-BT) from 22 studies were included (cases series = 13, case–control = 7, randomized control trial = 1, prospective cohort study = 1). The mean MINORS score was 13.2 ± 3.2. The mean age and follow-up were 67 ± 6.8 years and 4.58 ± 1.1 years (range, 2, 12), respectively. The VAS improvement showed at the last follow-up for PCR-BT (range, 1.97, 5.8) and BT (range, 4, 6.1). CMS was improved at the final follow-up for PCR-BT (range, 13, 47.6) and BT (range, 10.8, 28). Regarding the ASES, it has demonstrated significant improvements for PCR-BT (range, 31.81, 44.8) and BT (range, 30,45.8). For forward flexion, PCR-BT showed improvement (range, −14°, 59.4°), as well as the BT group (range, 2°, 27.9°). Conclusions: This systematic review demonstrated that both BT and PCR-BT improve functional outcomes and reduce pain at midterm follow-up for MIRCT. Since we know that a failed cuff repair would worsen the shoulder, it might be beneficial in terms of the risk–benefit ratio to not repair in certain patients with MIRCT.