Purpose: The purpose of this study was to develop a suicide prevention nursing competency program for visiting nurses, and to examine the effect of this program on suicide prevention-related knowledge, attitudes, and behaviors. Methods: A total of 66 visiting nurses were recruited from 10 public health centers and divided equally into the experimental and control group. For the experimental group, the suicide prevention nursing competency program was provided twice a week for 120 minutes across 3 weeks. Participants were asked questions related to suicide prevention knowledge, attitudes, and behaviors at pre, post, and 1 month after the intervention. Data were analyzed using descriptive statistics, a t-test, repeated measure ANOVA, and Friedman test. Results: There were significant differences in knowledge and behaviors at the measured time periods, and significant differences in attitudes and behaviors between the two groups. There were also significant interactions between groups and times in attitudes and behaviors. These results suggest that the effects of the program were persistent until the 1-month follow-up. Conclusion: The developed suicide prevention nursing competency program is effective in evidence-based education for visiting nurses to increase suicide prevention-related knowledge, attitudes, and behaviors.