The aim of this randomized controlled trial was to develop a web-based acute pain management education program for nurses and to evaluate its effectiveness. The developed program consisted of a total duration of 400 min with eight modules and 29 topics in pain management. Fifty nurses from the post-anesthesia care unit in two university-affiliated hospitals in Seoul, Korea were randomly assigned to either the experimental group (n = 25) or the control group (n = 25) and a total of 46 nurses, 23 for each group, completed the pre and post-tests. The pre and post-tests were performed to evaluate the changes of the nurses' knowledge, attitude, and self-efficacy regarding acute pain management. The experimental group showed a significant increase in knowledge and in self-efficacy about pain management compared to the control group (u = 389.0, p = .006; u = 360.0, p = .030, respectively). The results support the effective use of these web-based modules as part of a continuing education program on pain management for nurses working in an acute care setting. The findings of this study can be the basis for the development of evidence-based guidelines and training tailored to the Korean culture and similar settings.