Objective: To investigate the short-term clinical efficacy and surgical safety of single-plane retroperitoneal laparoscopic adrenalectomy for adrenal adenomas with a diameter ≤ 5 cm, and to provide an objective basis for the selection of clinical minimally invasive surgical procedures. Methods: A total of 50 patients with unilateral adrenal adenomas (all with tumor diameters ≤ 5 cm) who were admitted to our hospital between December 2020 and December 2025 were selected as study subjects. They were randomly assigned to an observation group (25 cases) and a control group (25 cases) using a random number table. The observation group underwent single-plane retroperitoneal laparoscopic adrenalectomy, while the control group underwent traditional multi-plane retroperitoneal laparoscopic adrenalectomy. Surgical-related indicators (operative time, intraoperative blood loss, and intraoperative conversion to open surgery rate), postoperative recovery indicators (postoperative drainage tube indwelling time, time to ambulation after surgery, postoperative hospital stay, and postoperative pain score), the incidence of postoperative complications, and changes in adrenal-related biochemical indicators before and after surgery were compared between the two groups. Results: All surgeries were successfully completed without any cases requiring conversion to open surgery during the operation. The operative time and intraoperative blood loss in the observation group were significantly better than those in the control group (p < 0.05). The postoperative drainage tube indwelling time, time to ambulation, and hospital stay in the observation group were significantly shorter than those in the control group, and the 24-hour postoperative Visual Analog Scale (VAS) pain score was significantly lower in the observation group (all p < 0.001). The incidence of complications in the observation group was lower than that in the control group, but the difference was not statistically significant (χ² = 2.000, p = 0.157 > 0.05). One week after surgery, the aforementioned indicators in both groups had significantly improved compared with their pre-surgery values (p < 0.05). There was no significant difference in the biochemical indicators between the two groups one week after surgery (p > 0.05). Conclusion: Single-plane retroperitoneal laparoscopic adrenalectomy for adrenal adenomas ≤ 5 cm in diameter can significantly shorten operative time, reduce intraoperative blood loss, accelerate postoperative recovery, and lower the risk of postoperative complications. It has definite short-term efficacy and high safety, and the operation is simpler, making it suitable for clinical promotion and application.