This study was conducted to explore the effect of video-based simulation training on postoperative patient care, clinical decision-making, and the competency levels of nursing students. The study was conducted as a randomized controlled trial. The sample of the study consisted of students (n=87) attending the nursing department of the health sciences faculty of a state university located in the Eastern Black Sea Region of Turkey. The data were collected with the “Student Information Form”, the “Postoperative Patient Care Knowledge Test”, the “Clinical Decision-Making in Nursing Scale (CDMNS)”, and the “Competency Inventory of Nursing Students (CINS)”. The postoperative patient care knowledge test scores of the experimental group students were statistically significantly higher than those of the control group (p<0.001). The CDMNS scores of the experimental group students were statistically significantly higher than those of the control group (p=0.024). There was no statistically significant difference between the CINS scores of the experimental and control groups. The results showed that the use of video simulation contributed positively to students' postoperative patient care and clinical decision-making.