Background Tonsillectomy is associated with significant pain, and postoperative pain control is often unsatisfactory. There have been several methods adopted to treat postoperative pain, but none of the methods were effective, with patients continuing to undergo severe postoperative pain. Hence, our study aimed to compare the efficacy of pre-emptive nebulized ketamine versus pre-emptive nebulized lidocaine with a control group receiving nebulized saline for pain control in children undergoing tonsillectomy. Methods In this prospective randomized clinical trial, 105 patients with American Society of Anesthesiologists(ASA) Ⅰ and Ⅱ undergoing tonsillectomy were enrolled and randomized into three groups, group K, group L, and group C, with 35 patients in each group, wherein pre-emptive nebulized ketamine, lidocaine, and saline were given to each group of patients, respectively. Faces Pain Scale-Revised (FPS-R), sedation scale scores, and the usage of rescue analgesia were noted postoperatively for the first six hours. Hemodynamic parameters were noted before and after nebulization.The primary objective was to determine the number of patients requiring rescue analgesia as an indicator of postoperative pain control. Results In this randomized clinical trial, pre-emptive nebulized ketamine significantly reduced the need for rescue analgesia compared to lidocaine and saline (p<0.05). Only 14.3% (n=5) of patients in the ketamine group required rescue analgesiacompared to 85.7% (n=30) in the lidocaine group and 91.4% (n=32) in the control group. Nebulized ketamine given pre-emptively is an effective strategy for reducing postoperative pain in pediatric tonsillectomy. Conclusion Pre-emptive nebulized ketamine was found to be effectivewhen compared with lidocaine nebulization in reducing postoperative pain in children undergoing tonsillectomy.