Thoracic outlet syndrome (TOS) consists of a group of disorders resulting from compression of the neurovascular bundle exiting through the thoracic outlet. TOS can be classified as follows based on the etiology of the pathophysiology: neurogenic TOS, venous TOS, arterial TOS, and mixed TOS. The constellation of symptoms a patient may experience varies, depending on the structures involved. Due to the wide range of etiologies and presenting symptoms, treatments for TOS also differ. Furthermore, most studies focus on the perioperative and short-term outcomes after surgical decompression for TOS. This systematic review aimed to provide a pooled analysis of studies to better understand the intermediate and long-term outcomes of surgical decompression for TOS. We conducted a systematic literature search in the Ovid MEDLINE, Embase, and Google Scholar databases for studies that analyzed long-term outcomes after surgical decompression for TOS. The inclusion period was from January 2015 to May 2023. The primary outcome was postoperative QuickDASH Outcome Measure scores. A total of 16 studies were included in the final analysis. The differences between postoperative and preoperative QuickDASH Outcome Measure scores were calculated, when possible, and there was a mean overall difference of 33.5 points (95% CI, 25.2–41.8; P = .001) after surgical decompression. There was a higher proportion of excellent outcomes reported for patients undergoing intervention for arterial and mixed TOS etiologies, whereas those with venous and neurogenic etiologies had the lowest proportion of excellent outcomes reported. Patients with neurogenic TOS had the highest proportion of poor outcomes reported. In conclusion, surgical decompression for TOS has favorable long-term outcomes, especially in patients with arterial and mixed etiologies.