Pathological obesity is a growing public health concern, and its association with gastroesophageal reflux disease (GERD) poses challenges in selecting the appropriate bariatric procedure. Sleeve gastrectomy (SG) has become a popular choice due to its simplicity and effectiveness in weight loss. However, concerns regarding postoperative GERD have been raised. This study aimed to evaluate the association between preoperative assessment of esophageal function and the risk of developing postoperative GERD in patients undergoing SG. A comprehensive evaluation was conducted, including symptom assessment, upper endoscopy, high-resolution esophageal manometry (HRM), and 24 h esophageal pH impedance monitoring (MII-pH). A total of 500 obese patients were included, and their data were compared with 25 healthy volunteers. This study revealed that patients without GERD symptoms, normal endoscopy, HRM, and MII-pH were suitable candidates for SG, with low risk of developing postoperative GERD. The addition of fundoplication techniques to SG may be considered in patients with mild reflux or those at risk of developing it. This study emphasizes the importance of preoperative evaluation in selecting the appropriate bariatric procedure to minimize the risk of postoperative GERD and expand the indications for SG in obese patients.