Purpose <p>To compare postoperative range of motion (ROM), pain and functional outcomes in patients immobilized with an abduction neutral rotation brace (ANRB) versus a conventional arm sling following arthroscopic rotator cuff repair (ARCR).</p> Methods <p>Thirty patients aged 40–75&#xa0;years with full-thickness supraspinatus and/or infraspinatus tear undergoing ARCR were randomized to immobilized using either an abduction neutral rotation brace (n = 16) or a conventional arm sling (n = 16). Outcomes including ROM, visual analogue scale (VAS) for pain, and Constant-Murley score (CMS) were assessed preoperatively and at 6&#xa0;weeks, 3, 6, and 12&#xa0;months postoperatively.</p> Results <p>At 3&#xa0;months, patients in the abduction neutral rotation brace group demonstrated significantly greater forward flexion and external rotation compared to the arm sling group (<i>P</i> &lt; 0.05). VAS pain scores were significantly lower at 6&#xa0;weeks and 6&#xa0;months in the brace group (<i>P</i> &lt; 0.05). CMS showed no significant difference between groups at final follow-up. No re-tears or complications were observed in either group.</p> Conclusion <p>Use of an abduction neutral rotation brace after ARCR results in improved early postoperative ROM and pain control compared to a conventional arm sling. This technique may facilitate earlier rehabilitation and higher patient satisfaction.</p> Level of evidence <p>Level I; Randomized Controlled Trial.</p>