Nasogastric intubation is a common procedure in hospitals that causes adverse outcomes if performed incorrectly. There is currently insufficient guidance for patient positioning, which increases the success of nasogastric intubation at the bedside. Therefore, a systematic review with a meta-analysis was performed to determine the effectiveness of changing an unconscious adults' positions compared with the supine position to improve the correct placement of a nasogastric tube, intubation time, and complications. The Cochrane Library, MEDLINE, Embase, PubMed, and CINAHL databases were searched from inception to April 2019 for randomized controlled trials. The Cochrane Collaboration Risk of Bias tool was used to assess the quality of eligible studies. Cochrane Review Manager 5.3 software was used to analyze the data. A total of 288 articles were obtained in the literature search, 10 of which were included in the analysis. Most of the included trials were at low risk of bias. All postures were significantly effective, though neck flexion had the highest success rate (odds ratio = 4.87, 95% confidence interval [2.48, 9.57], Z = 4.6, p < .00001, I2 = 0%) for nasogastric intubation. In terms of the time required for the procedure, compared with the usual posture, although the total effects were significant ( MD =-10.33, 95% confidence interval [-15.38, -5.29], Z = 4.02, p < .00001, I2 = 98%), only neck flexion and lifting of the larynx reduced the time. The meta-analysis suggests that patient positioning improves the success rate of nasogastric intubation and increases safety. Finally, the authors developed a procedural instruction sheet to aid practitioners with nasogastric intubation.