Patients with heart disease often feel helpless and anxious because of illnesses in their vital organs. Unfamiliar environment of the intensive care unit is another factor that increases patient anxiety. This study developed audiovisual media-based information on nursing after open-heart surgery and evaluated its effect on patients’ post-surgery, with the aim of reducing patients’ environmental stress, anxiety, and uncertainty. This quasi-experimental study was conducted using a nonequivalent control group and non-synchronized pretest-posttest design to investigate the effect of audiovisual media-based nursing information provided prior to surgery on environmental stress, anxiety, and uncertainty in patients admitted to the cardiovascular intensive care unit after open-heart surgery. This study included 147 patients with heart disease who underwent open-heart surgery at a university hospital in South Korea. Dropouts in each group were caused by the following: for the control group, 2 were due to death, 9 discontinued, and 5 lost consciousness; for the experimental group, 2 were due to death, 6 discontinued, and 2 lost consciousness. The final number of participants investigated was 121 to 65 in the experimental group and 56 in the control group. Prior to surgery, the experimental group was provided with audio-visual information about nursing, whereas the control group was provided with written information about nursing. The environmental stress score was lower in the experimental group, 1.95 ± 0.51 points compared to 2.31 ± 0.51 points in the control group (t = 3.38, P < .001). There was a significant difference in anxiety between the mean pretest-posttest scores, with 0.39 ± 0.35 points in the experimental group, and −0.05 ± 0.58 points in the control group (t = 5.165, P < .001). On the other hand, there was a significant difference in uncertainty between the mean pretest-posttest scores, with 0.39 ± 0.4 points in the experimental group, and 0.24 ± 0.48 points in the control group (t = 4.541, P < .001). This finding indicates that providing audiovisual information regarding nursing before open-heart surgery is effective in reducing environmental stress, anxiety, and uncertainty in patients.