Background/Objectives: Sinus elevation in the posterior maxilla carries a risk of hemorrhage due to injury of the posterior superior alveolar artery (PSAA). Accurate preoperative identification of the PSAA using cone-beam computed tomography (CBCT) can enhance surgical safety. This retrospective study evaluated the prevalence, location, diameter, and visibility of the PSAA in a Saudi population. Methods: A total of 117 CBCT scans (234 sinuses) obtained between 2022 and 2024 were analyzed. The PSAA's visibility, diameter, and distances from the alveolar crest, sinus floor, medial wall, and sinus septa were measured. Associations with age, sex, smoking status, and the presence of sinus septa were statistically assessed. Results: The PSAA was identified in 98.3% of sinuses. Intraosseous and submucosal locations predominated in premolar and molar regions, respectively. Class A arteries (≤1 mm) were most frequent. Significant differences were found between premolar and molar regions in arterial location and distances from the alveolar crest and sinus walls (p < 0.001). Older individuals exhibited medial displacement of the artery in the molar region, and smokers showed significantly smaller diameters (p < 0.05). Sinus septa were associated with increased PSAA distances from the sinus floor and medial wall. Conclusions: The PSAA demonstrates high detectability and marked variability in position and caliber within this Saudi cohort. Recognition of these anatomical variations is essential for reducing complications during sinus-augmentation procedures.